mirror of
https://github.com/michaelrsweet/pdfio.git
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395 lines
8.7 KiB
C
395 lines
8.7 KiB
C
//
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// Common support functions for pdfio.
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//
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// Copyright © 2021 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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//
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// Include necessary headers...
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//
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#include "pdfio-private.h"
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//
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// Local functions...
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//
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static bool fill_buffer(pdfio_file_t *pdf);
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static ssize_t read_buffer(pdfio_file_t *pdf, char *buffer, size_t bytes);
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static bool write_buffer(pdfio_file_t *pdf, const char *buffer, size_t bytes);
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//
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// '_pdfioFileDefaultError()' - Default error callback.
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//
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// The default error callback writes the error message to stderr and returns
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// `false` to halt.
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//
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bool // O - `false` to stop
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_pdfioFileDefaultError(
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pdfio_file_t *pdf, // I - PDF file
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const char *message, // I - Error message
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void *data) // I - Callback data (unused)
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{
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(void)data;
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fprintf(stderr, "%s: %s\n", pdf->filename, message);
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return (false);
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}
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//
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// '_pdfioFileError()' - Display an error message.
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//
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bool // O - `true` to continue, `false` to stop
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_pdfioFileError(pdfio_file_t *pdf, // I - PDF file
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const char *format, // I - `printf`-style format string
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...) // I - Additional arguments as needed
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{
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char buffer[8192]; // Message buffer
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va_list ap; // Argument pointer
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va_start(ap, format);
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vsnprintf(buffer, sizeof(buffer), format, ap);
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va_end(ap);
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return ((pdf->error_cb)(pdf, buffer, pdf->error_data));
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}
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//
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// '_pdfioFileFlush()' - Flush any pending write data.
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//
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bool // O - `true` on success, `false` on failure
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_pdfioFileFlush(pdfio_file_t *pdf) // I - PDF file
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{
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if (pdf->bufptr > pdf->buffer)
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{
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if (!write_buffer(pdf, pdf->buffer, (size_t)(pdf->bufptr - pdf->buffer)))
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return (false);
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pdf->bufpos += pdf->bufptr - pdf->buffer;
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pdf->bufptr = pdf->buffer;
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}
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return (true);
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}
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//
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// '_pdfioFileGetChar()' - Get a character from a PDF file.
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//
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int // O - Character or `-1` on EOF
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_pdfioFileGetChar(pdfio_file_t *pdf) // I - PDF file
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{
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// If there is a character ready in the buffer, return it now...
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if (pdf->bufptr < pdf->bufend)
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return (*(pdf->bufptr ++));
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// Otherwise try to fill the read buffer...
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if (!fill_buffer(pdf))
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return (-1);
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// Then return the next character in the buffer...
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return (*(pdf->bufptr ++));
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}
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//
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// '_pdfioFilePrintf()' - Write a formatted string to a PDF file.
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//
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bool // O - `true` on success, `false` on failure
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_pdfioFilePrintf(pdfio_file_t *pdf, // I - PDF file
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const char *format, // I - `printf`-style format string
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...) // I - Additional arguments as needed
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{
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char buffer[8102]; // String buffer
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va_list ap; // Argument list
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// Format the string...
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va_start(ap, format);
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vsnprintf(buffer, sizeof(buffer), format, ap);
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va_end(ap);
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// Write it...
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return (_pdfioFileWrite(pdf, buffer, strlen(buffer)));
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}
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//
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// '_pdfioFilePuts()' - Write a literal string to a PDF file.
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//
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bool // O - `true` on success, `false` on failure
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_pdfioFilePuts(pdfio_file_t *pdf, // I - PDF file
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const char *s) // I - Literal string
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{
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// Write it...
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return (_pdfioFileWrite(pdf, s, strlen(s)));
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}
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//
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// '_pdfioFileRead()' - Read from a PDF file.
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//
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ssize_t // O - Number of bytes read or `-1` on error
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_pdfioFileRead(pdfio_file_t *pdf, // I - PDF file
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char *buffer, // I - Read buffer
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size_t bytes) // I - Number of bytes to read
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{
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ssize_t total, // Total bytes read
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rbytes; // Bytes read this time
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// Loop until we have read all of the requested bytes or hit an error...
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for (total = 0; bytes > 0; total += rbytes, bytes -= (size_t)rbytes, buffer += rbytes)
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{
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// First read from the file buffer...
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if ((rbytes = pdf->bufend - pdf->bufptr) > 0)
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{
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if ((size_t)rbytes > bytes)
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rbytes = (ssize_t)bytes;
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memcpy(buffer, pdf->bufptr, rbytes);
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pdf->bufptr += rbytes;
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continue;
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}
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// Nothing buffered...
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if (bytes > 1024)
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{
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// Read directly from the file...
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if ((rbytes = read_buffer(pdf, buffer, bytes)) > 0)
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{
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pdf->bufpos += rbytes;
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continue;
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}
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else
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break;
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}
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else
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{
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// Fill buffer and try again...
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if (!fill_buffer(pdf))
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break;
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}
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}
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return (total);
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}
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//
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// '_pdfioFileSeek()' - Seek within a PDF file.
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//
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off_t // O - New offset from beginning of file or `-1` on error
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_pdfioFileSeek(pdfio_file_t *pdf, // I - PDF file
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off_t offset, // I - Offset
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int whence) // I - Offset base
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{
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// Adjust offset for relative seeks...
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if (whence == SEEK_CUR)
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{
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offset += pdf->bufpos;
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whence = SEEK_SET;
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}
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if (pdf->mode == _PDFIO_MODE_READ)
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{
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// Reading, see if we already have the data we need...
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if (whence != SEEK_END && offset >= pdf->bufpos && offset < (pdf->bufpos + pdf->bufend - pdf->buffer))
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{
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// Yes, seek within existing buffer...
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pdf->bufptr = pdf->buffer + offset - pdf->bufpos;
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return (offset);
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}
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// No, reset the read buffer
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pdf->bufptr = pdf->bufend = NULL;
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}
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else
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{
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// Writing, make sure we write any buffered data...
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if (pdf->bufptr > pdf->buffer)
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{
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if (!write_buffer(pdf, pdf->buffer, (size_t)(pdf->bufptr - pdf->buffer)))
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return (-1);
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}
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pdf->bufptr = pdf->buffer;
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}
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// Seek within the file...
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if ((offset = lseek(pdf->fd, offset, whence)) < 0)
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{
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_pdfioFileError(pdf, "Unable to seek within file - %s", strerror(errno));
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return (-1);
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}
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pdf->bufpos = offset;
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return (offset);
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}
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//
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// '_pdfioFileTell()' - Return the offset within a PDF file.
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//
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off_t // O - Offset from beginning of file
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_pdfioFileTell(pdfio_file_t *pdf) // I - PDF file
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{
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if (pdf->bufptr)
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return (pdf->bufpos + (pdf->bufptr - pdf->buffer));
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else
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return (pdf->bufpos);
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}
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//
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// '_pdfioFileWrite()' - Write to a PDF file.
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//
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bool // O - `true` on success and `false` on error
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_pdfioFileWrite(pdfio_file_t *pdf, // I - PDF file
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const char *buffer, // I - Write buffer
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size_t bytes) // I - Bytes to write
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{
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// See if the data will fit in the write buffer...
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if (bytes > (size_t)(pdf->bufend - pdf->bufptr))
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{
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// No room, flush any current data...
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if (!_pdfioFileFlush(pdf))
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return (false);
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if (bytes >= sizeof(pdf->buffer))
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{
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// Write directly...
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if (!write_buffer(pdf, buffer, bytes))
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return (false);
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pdf->bufpos += bytes;
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return (true);
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}
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}
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// Copy data to the buffer and return...
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memcpy(pdf->bufptr, buffer, bytes);
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pdf->bufptr += bytes;
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return (true);
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}
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//
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// 'fill_buffer()' - Fill the read buffer in a PDF file.
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//
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static bool // O - `true` on success, `false` on failure
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fill_buffer(pdfio_file_t *pdf) // I - PDF file
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{
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ssize_t bytes; // Bytes read...
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// Advance current position in file as needed...
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if (pdf->bufend)
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pdf->bufpos += pdf->bufend - pdf->buffer;
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// Try reading from the file...
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if ((bytes = read_buffer(pdf, pdf->buffer, sizeof(pdf->buffer))) <= 0)
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{
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// EOF or hard error...
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pdf->bufptr = pdf->bufend = NULL;
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return (false);
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}
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else
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{
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// Successful read...
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pdf->bufptr = pdf->buffer;
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pdf->bufend = pdf->buffer + bytes;
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return (true);
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}
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}
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//
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// 'read_buffer()' - Read a buffer from a PDF file.
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//
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static ssize_t // O - Number of bytes read or -1 on error
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read_buffer(pdfio_file_t *pdf, // I - PDF file
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char *buffer, // I - Buffer
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size_t bytes) // I - Number of bytes to read
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{
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ssize_t rbytes; // Bytes read...
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// Read from the file...
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while ((rbytes = read(pdf->fd, buffer, bytes)) < 0)
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{
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// Stop if we have an error that shouldn't be retried...
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if (errno != EINTR && errno != EAGAIN)
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break;
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}
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if (rbytes < 0)
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{
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// Hard error...
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_pdfioFileError(pdf, "Unable to read from file - %s", strerror(errno));
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}
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return (rbytes);
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}
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//
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// 'write_buffer()' - Write a buffer to a PDF file.
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//
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static bool // O - `true` on success and `false` on error
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write_buffer(pdfio_file_t *pdf, // I - PDF file
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const char *buffer, // I - Write buffer
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size_t bytes) // I - Bytes to write
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{
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ssize_t wbytes; // Bytes written...
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// Write to the file...
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while (bytes > 0)
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{
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while ((wbytes = write(pdf->fd, buffer, bytes)) < 0)
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{
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// Stop if we have an error that shouldn't be retried...
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if (errno != EINTR && errno != EAGAIN)
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break;
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}
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if (wbytes < 0)
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{
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// Hard error...
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_pdfioFileError(pdf, "Unable to write to file - %s", strerror(errno));
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return (false);
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}
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buffer += wbytes;
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bytes -= wbytes;
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}
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return (true);
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}
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