mirror of
https://github.com/michaelrsweet/pdfio.git
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679 lines
14 KiB
C
679 lines
14 KiB
C
//
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// PDF token parsing functions for PDFio.
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//
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// Copyright © 2021-2023 by Michael R Sweet.
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//
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// Licensed under Apache License v2.0. See the file "LICENSE" for more
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// information.
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//
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#include "pdfio-private.h"
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//
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// This file parses PDF language syntax:
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//
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// << dict >> "<<" and ">>" delimit a dictionary
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// (string) "(" and ")" delimit a string
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// [array] "[" and "]" delimit an array
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// <hex-string> "<" and ">" delimit a hex string
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// {...} "{" and "}" are reserved as future delimiters
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// /name "/" starts a name with any special characters
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// quoted as "#HH" where HH is the byte value in hex.
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// %comment "%" starts a comment to the end of a line
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// keyword A keyword consists of other unreserved characters
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// [-+]?[0-9]*(.[0-9]*)? A number optionally starts with "+" or "-".
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//
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// Newlines are CR, LF, or CR LF.
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//
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// Strings and names are returned with the leading delimiter ("(string",
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// "<hex-string", "/name") and all escaping/whitespace removal resolved.
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// Other delimiters, keywords, and numbers are returned as-is.
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//
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//
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// Constants...
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//
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#define PDFIO_NUMBER_CHARS "0123456789-+."
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#define PDFIO_DELIM_CHARS "<>(){}[]/%"
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//
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// Local functions...
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//
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static int get_char(_pdfio_token_t *tb);
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//
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// '_pdfioTokenClear()' - Clear the token stack.
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//
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void
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_pdfioTokenClear(_pdfio_token_t *tb) // I - Token buffer/stack
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{
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PDFIO_DEBUG("_pdfioTokenClear(tb=%p)\n", tb);
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while (tb->num_tokens > 0)
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{
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tb->num_tokens --;
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free(tb->tokens[tb->num_tokens]);
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tb->tokens[tb->num_tokens] = NULL;
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}
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}
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//
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// '_pdfioTokenFlush()' - Flush (consume) any bytes that have been used.
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//
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void
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_pdfioTokenFlush(_pdfio_token_t *tb) // I - Token buffer/stack
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{
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if (tb->bufptr > tb->buffer)
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{
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size_t remaining = (size_t)(tb->bufend - tb->bufptr);
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// Remaining bytes in buffer
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// Consume what we've used...
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PDFIO_DEBUG("_pdfioTokenFlush: Consuming %d bytes.\n", (int)(tb->bufptr - tb->buffer));
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(tb->consume_cb)(tb->cb_data, (size_t)(tb->bufptr - tb->buffer));
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if (remaining > 0)
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{
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// Shuffle remaining bytes for next call...
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memmove(tb->buffer, tb->bufptr, remaining);
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tb->bufptr = tb->buffer;
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tb->bufend = tb->buffer + remaining;
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#ifdef DEBUG
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unsigned char *ptr; // Pointer into buffer
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PDFIO_DEBUG("_pdfioTokenFlush: Remainder '");
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for (ptr = tb->buffer; ptr < tb->bufend; ptr ++)
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{
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if (*ptr < ' ' || *ptr == 0x7f)
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PDFIO_DEBUG("\\%03o", *ptr);
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else
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PDFIO_DEBUG("%c", *ptr);
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}
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PDFIO_DEBUG("'\n");
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#endif // DEBUG
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}
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else
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{
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// Nothing left, reset pointers...
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PDFIO_DEBUG("_pdfioTokenFlush: Resetting pointers.\n");
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tb->bufptr = tb->bufend = tb->buffer;
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}
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}
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}
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//
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// '_pdfioTokenGet()' - Get a token.
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//
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bool // O - `true` on success, `false` on failure
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_pdfioTokenGet(_pdfio_token_t *tb, // I - Token buffer/stack
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char *buffer, // I - String buffer
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size_t bufsize) // I - Size of string buffer
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{
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// See if we have a token waiting on the stack...
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if (tb->num_tokens > 0)
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{
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// Yes, return it...
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size_t len; // Length of token
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tb->num_tokens --;
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if ((len = strlen(tb->tokens[tb->num_tokens])) > (bufsize - 1))
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{
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// Value too large...
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PDFIO_DEBUG("_pdfioTokenGet(tb=%p, buffer=%p, bufsize=%u): Token '%s' from stack too large.\n", tb, buffer, (unsigned)bufsize, tb->tokens[tb->num_tokens]);
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*buffer = '\0';
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return (false);
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}
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memcpy(buffer, tb->tokens[tb->num_tokens], len);
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buffer[len] = '\0';
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PDFIO_DEBUG("_pdfioTokenGet(tb=%p, buffer=%p, bufsize=%u): Popping '%s' from stack.\n", tb, buffer, (unsigned)bufsize, buffer);
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free(tb->tokens[tb->num_tokens]);
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tb->tokens[tb->num_tokens] = NULL;
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return (true);
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}
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// No, read a new one...
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return (_pdfioTokenRead(tb, buffer, bufsize));
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}
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//
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// '_pdfioTokenInit()' - Initialize a token buffer/stack.
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//
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void
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_pdfioTokenInit(
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_pdfio_token_t *ts, // I - Token buffer/stack
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pdfio_file_t *pdf, // I - PDF file
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_pdfio_tconsume_cb_t consume_cb, // I - Consume callback
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_pdfio_tpeek_cb_t peek_cb, // I - Peek callback
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void *cb_data) // I - Callback data
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{
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// Zero everything out and then initialize key pointers...
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memset(ts, 0, sizeof(_pdfio_token_t));
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ts->pdf = pdf;
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ts->consume_cb = consume_cb;
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ts->peek_cb = peek_cb;
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ts->cb_data = cb_data;
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ts->bufptr = ts->buffer;
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ts->bufend = ts->buffer;
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}
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//
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// '_pdfioTokenPush()' - Push a token on the token stack.
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//
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void
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_pdfioTokenPush(_pdfio_token_t *tb, // I - Token buffer/stack
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const char *token) // I - Token to push
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{
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if (tb->num_tokens < (sizeof(tb->tokens) / sizeof(tb->tokens[0])))
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{
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if ((tb->tokens[tb->num_tokens ++] = strdup(token)) == NULL)
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tb->num_tokens --;
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}
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}
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//
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// '_pdfioTokenRead()' - Read a token from a file/stream.
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//
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bool // O - `true` on success, `false` on failure
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_pdfioTokenRead(_pdfio_token_t *tb, // I - Token buffer/stack
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char *buffer, // I - String buffer
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size_t bufsize) // I - Size of string buffer
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{
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int ch, // Character
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parens = 0; // Parenthesis level
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char *bufptr, // Pointer into buffer
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*bufend, // End of buffer
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state = '\0'; // Current state
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bool saw_nul = false; // Did we see a nul character?
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size_t count = 0; // Number of whitespace/comment bytes
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// "state" is:
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//
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// - '\0' for idle
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// - '(' for literal string
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// - '/' for name
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// - '<' for possible hex string or dict
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// - '>' for possible dict
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// - '%' for comment
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// - 'K' for keyword
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// - 'N' for number
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// Read the next token, skipping any leading whitespace...
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bufptr = buffer;
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bufend = buffer + bufsize - 1;
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// Skip leading whitespace...
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while ((ch = get_char(tb)) != EOF)
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{
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count ++;
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if (ch == '%')
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{
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// Skip comment
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PDFIO_DEBUG("_pdfioTokenRead: Skipping comment...\n");
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while ((ch = get_char(tb)) != EOF)
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{
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count ++;
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if (ch == '\n' || ch == '\r')
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{
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break;
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}
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else if (count > 2048)
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{
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_pdfioFileError(tb->pdf, "Comment too long.");
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*bufptr = '\0';
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return (false);
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}
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}
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}
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else if (!isspace(ch))
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{
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break;
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}
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else if (count > 2048)
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{
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_pdfioFileError(tb->pdf, "Too much whitespace.");
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*bufptr = '\0';
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return (false);
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}
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}
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if (ch == EOF)
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{
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*bufptr = '\0';
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return (false);
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}
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// Check for delimiters...
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if (strchr(PDFIO_DELIM_CHARS, ch) != NULL)
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{
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*bufptr++ = state = (char)ch;
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}
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else if (strchr(PDFIO_NUMBER_CHARS, ch) != NULL)
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{
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// Number
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state = 'N';
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*bufptr++ = (char)ch;
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}
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else
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{
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// Keyword
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state = 'K';
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*bufptr++ = (char)ch;
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}
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PDFIO_DEBUG("_pdfioTokenRead: state='%c'\n", state);
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switch (state)
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{
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case '(' : // Literal string
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while ((ch = get_char(tb)) != EOF)
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{
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if (ch == 0)
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saw_nul = true;
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if (ch == '\\')
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{
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// Quoted character...
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int i; // Looping var
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switch (ch = get_char(tb))
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{
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case '0' : // Octal character escape
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case '1' :
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case '2' :
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case '3' :
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case '4' :
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case '5' :
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case '6' :
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case '7' :
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for (ch -= '0', i = 0; i < 2; i ++)
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{
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int tch = get_char(tb); // Next char
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if (tch >= '0' && tch <= '7')
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{
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ch = (char)((ch << 3) | (tch - '0'));
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}
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else
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{
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tb->bufptr --;
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break;
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}
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}
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break;
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case '\\' :
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case '(' :
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case ')' :
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break;
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case 'n' :
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ch = '\n';
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break;
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case 'r' :
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ch = '\r';
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break;
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case 't' :
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ch = '\t';
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break;
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case 'b' :
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ch = '\b';
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break;
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case 'f' :
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ch = '\f';
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break;
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default :
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// Ignore blackslash per PDF spec...
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break;
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}
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}
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else if (ch == '(')
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{
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// Keep track of parenthesis
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parens ++;
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}
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else if (ch == ')')
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{
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if (parens == 0)
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break;
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parens --;
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}
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if (bufptr < bufend)
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{
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// Normal character...
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*bufptr++ = (char)ch;
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}
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else
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{
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// Out of space
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_pdfioFileError(tb->pdf, "Token too large.");
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*bufptr = '\0';
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return (false);
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}
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}
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if (ch != ')')
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{
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_pdfioFileError(tb->pdf, "Unterminated string literal.");
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*bufptr = '\0';
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return (false);
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}
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if (saw_nul)
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{
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// Convert to a hex (binary) string...
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char *litptr, // Pointer to literal character
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*hexptr; // Pointer to hex character
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size_t bytes = (size_t)(bufptr - buffer - 1);
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// Bytes of data...
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static const char *hexchars = "0123456789ABCDEF";
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// Hex digits
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PDFIO_DEBUG("_pdfioTokenRead: Converting nul-containing string to binary.\n");
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if ((2 * (bytes + 1)) > bufsize)
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{
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// Out of space...
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_pdfioFileError(tb->pdf, "Token too large.");
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*bufptr = '\0';
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return (false);
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}
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*buffer = '<';
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for (litptr = bufptr - 1, hexptr = buffer + 2 * bytes - 1; litptr > buffer; litptr --, hexptr -= 2)
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{
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int litch = *litptr; // Grab the character
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hexptr[0] = hexchars[(litch >> 4) & 15];
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hexptr[1] = hexchars[litch & 15];
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}
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bufptr = buffer + 2 * bytes + 1;
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}
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break;
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case 'K' : // keyword
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while ((ch = get_char(tb)) != EOF && !isspace(ch))
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{
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if (strchr(PDFIO_DELIM_CHARS, ch) != NULL)
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{
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// End of keyword...
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tb->bufptr --;
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break;
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}
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else if (bufptr < bufend)
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{
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// Normal character...
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*bufptr++ = (char)ch;
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}
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else
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{
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// Out of space...
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_pdfioFileError(tb->pdf, "Token too large.");
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*bufptr = '\0';
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return (false);
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}
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}
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if (ch == '\r')
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{
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// Look for a trailing LF
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if ((ch = get_char(tb)) != EOF && ch != '\n')
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tb->bufptr --;
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}
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break;
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case 'N' : // number
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while ((ch = get_char(tb)) != EOF && !isspace(ch))
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{
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if (!isdigit(ch) && ch != '.')
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{
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// End of number...
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PDFIO_DEBUG("_pdfioTokenRead: End of number with ch=0x%02x\n", ch);
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tb->bufptr --;
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break;
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}
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else if (bufptr < bufend)
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{
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// Normal character...
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*bufptr++ = (char)ch;
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}
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else
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{
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// Out of space...
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_pdfioFileError(tb->pdf, "Token too large.");
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*bufptr = '\0';
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return (false);
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}
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}
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break;
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case '/' : // "/name"
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while ((ch = get_char(tb)) != EOF && !isspace(ch))
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{
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if (strchr(PDFIO_DELIM_CHARS, ch) != NULL)
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{
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// End of keyword...
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tb->bufptr --;
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break;
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}
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else if (ch == '#')
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{
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// Quoted character (#xx) in name...
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int i; // Looping var
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for (i = 0, ch = 0; i < 2; i ++)
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{
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int tch = get_char(tb);
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if (!isxdigit(tch & 255))
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{
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_pdfioFileError(tb->pdf, "Bad # escape in name.");
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*bufptr = '\0';
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return (false);
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}
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else if (isdigit(tch))
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{
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ch = ((ch & 255) << 4) | (tch - '0');
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}
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else
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{
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ch = ((ch & 255) << 4) | (tolower(tch) - 'a' + 10);
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}
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}
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}
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if (bufptr < bufend)
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{
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*bufptr++ = (char)ch;
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}
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else
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{
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// Out of space
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_pdfioFileError(tb->pdf, "Token too large.");
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*bufptr = '\0';
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return (false);
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}
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}
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if (bufptr == (buffer + 1))
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{
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_pdfioFileError(tb->pdf, "Empty name.");
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*bufptr = '\0';
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return (false);
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}
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break;
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case '<' : // Potential hex string
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if ((ch = get_char(tb)) == '<')
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{
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// Dictionary delimiter
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*bufptr++ = (char)ch;
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break;
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}
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else if (ch == '>')
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{
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// Issue #46: Empty hex string from Microsoft PDF generator; treat as
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// empty literal string...
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*buffer = '(';
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break;
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}
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else if (!isspace(ch & 255) && !isxdigit(ch & 255))
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{
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_pdfioFileError(tb->pdf, "Syntax error: '<%c'", ch);
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*bufptr = '\0';
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return (false);
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}
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count = 0;
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do
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{
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if (isxdigit(ch))
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{
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if (bufptr < bufend)
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{
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// Hex digit
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*bufptr++ = (char)ch;
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count = 0;
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}
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else
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{
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// Too large
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_pdfioFileError(tb->pdf, "Token too large.");
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*bufptr = '\0';
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return (false);
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}
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}
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else if (!isspace(ch))
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{
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_pdfioFileError(tb->pdf, "Invalid hex string character '%c'.", ch);
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*bufptr = '\0';
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return (false);
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}
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else
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{
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count ++;
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if (count > 2048)
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{
|
||
_pdfioFileError(tb->pdf, "Too much whitespace.");
|
||
*bufptr = '\0';
|
||
return (false);
|
||
}
|
||
}
|
||
}
|
||
while ((ch = get_char(tb)) != EOF && ch != '>');
|
||
|
||
if (ch == EOF)
|
||
{
|
||
_pdfioFileError(tb->pdf, "Unterminated hex string.");
|
||
*bufptr = '\0';
|
||
return (false);
|
||
}
|
||
break;
|
||
|
||
case '>' : // Dictionary
|
||
if ((ch = get_char(tb)) == '>')
|
||
{
|
||
*bufptr++ = '>';
|
||
}
|
||
else
|
||
{
|
||
_pdfioFileError(tb->pdf, "Syntax error: '>%c'.", ch);
|
||
*bufptr = '\0';
|
||
return (false);
|
||
}
|
||
break;
|
||
}
|
||
|
||
*bufptr = '\0';
|
||
|
||
PDFIO_DEBUG("_pdfioTokenRead: Read '%s'.\n", buffer);
|
||
|
||
return (bufptr > buffer);
|
||
}
|
||
|
||
|
||
//
|
||
// 'get_char()' - Get a character from the token buffer.
|
||
//
|
||
|
||
static int // O - Character or `EOF` on end-of-file
|
||
get_char(_pdfio_token_t *tb) // I - Token buffer
|
||
{
|
||
ssize_t bytes; // Bytes peeked
|
||
|
||
|
||
// Refill the buffer as needed...
|
||
if (tb->bufptr >= tb->bufend)
|
||
{
|
||
// Consume previous bytes...
|
||
if (tb->bufend > tb->buffer)
|
||
{
|
||
PDFIO_DEBUG("get_char: Consuming %d bytes.\n", (int)(tb->bufend - tb->buffer));
|
||
(tb->consume_cb)(tb->cb_data, (size_t)(tb->bufend - tb->buffer));
|
||
}
|
||
|
||
// Peek new bytes...
|
||
if ((bytes = (tb->peek_cb)(tb->cb_data, tb->buffer, sizeof(tb->buffer))) <= 0)
|
||
{
|
||
tb->bufptr = tb->bufend = tb->buffer;
|
||
return (EOF);
|
||
}
|
||
|
||
// Update pointers...
|
||
tb->bufptr = tb->buffer;
|
||
tb->bufend = tb->buffer + bytes;
|
||
|
||
#ifdef DEBUG
|
||
unsigned char *ptr; // Pointer into buffer
|
||
|
||
PDFIO_DEBUG("get_char: Read '");
|
||
for (ptr = tb->buffer; ptr < tb->bufend; ptr ++)
|
||
{
|
||
if (*ptr < ' ' || *ptr == 0x7f)
|
||
PDFIO_DEBUG("\\%03o", *ptr);
|
||
else
|
||
PDFIO_DEBUG("%c", *ptr);
|
||
}
|
||
PDFIO_DEBUG("'\n");
|
||
#endif // DEBUG
|
||
}
|
||
|
||
// Return the next character...
|
||
return (*(tb->bufptr)++);
|
||
}
|