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Safe work on streams - still need to implement predictors
This commit is contained in:
Michael R Sweet
parent
c61d6ad686
commit
44325ce2d9
3
TODO.md
3
TODO.md
@ -10,6 +10,9 @@ To-Do List
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one PDF to another, there are a bunch of resources that also need to be
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copied. A dictionary with an object reference can't be copied directly as the
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object number in the new PDF will likely be different than the old one.
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- Add _pdfio_map_t with original pdfio_file_t * and object numbers
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- Add _pdfioObjCopy function
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- Add _pdfioFileGetMappedObject function to get the new object number
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- Security handlers (RC4 + AES, MD5 + SHA-256) for reading encrypted documents.
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- Signature generation/validation code
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- Documentation
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89
pdfio-file.c
89
pdfio-file.c
@ -537,14 +537,19 @@ load_xref(pdfio_file_t *pdf, // I - PDF file
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return (false);
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}
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PDFIO_DEBUG("load_xref: xref_offset=%lu, line='%s'\n", (unsigned long)xref_offset, line);
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if (isdigit(line[0] & 255) && strlen(line) > 4 && !strcmp(line + strlen(line) - 4, " obj"))
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{
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// Cross-reference stream
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pdfio_obj_t *obj; // Object
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size_t i; // Looping var
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pdfio_array_t *w_array; // W array
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size_t w[3]; // Size of each cross-reference field
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size_t w_2, // Offset to second field
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w_3; // Offset to third field
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size_t w_total; // Total length
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pdfio_stream_t *st; // Stream with
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pdfio_stream_t *st; // Stream
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unsigned char buffer[32]; // Read buffer
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if ((number = strtoimax(line, &ptr, 10)) < 1)
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@ -568,6 +573,8 @@ load_xref(pdfio_file_t *pdf, // I - PDF file
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return (false);
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}
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PDFIO_DEBUG("load_xref: Loading object %lu %u.\n", (unsigned long)number, (unsigned)generation);
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if ((obj = add_obj(pdf, (size_t)number, (unsigned short)generation, xref_offset)) == NULL)
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{
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_pdfioFileError(pdf, "Unable to allocate memory for object.");
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@ -587,7 +594,85 @@ load_xref(pdfio_file_t *pdf, // I - PDF file
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obj->value = trailer;
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// TODO: read stream
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if (!_pdfioFileGetToken(pdf, line, sizeof(line)) || strcmp(line, "stream"))
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{
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_pdfioFileError(pdf, "Unable to get stream after xref dictionary.");
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return (false);
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}
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obj->stream_offset = _pdfioFileTell(pdf);
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if ((w_array = pdfioDictGetArray(trailer.value.dict, "W")) == NULL)
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{
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_pdfioFileError(pdf, "Cross-reference stream does not have required W key.");
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return (false);
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}
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w[0] = (size_t)pdfioArrayGetNumber(w_array, 0);
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w[1] = (size_t)pdfioArrayGetNumber(w_array, 1);
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w[2] = (size_t)pdfioArrayGetNumber(w_array, 2);
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w_total = w[0] + w[1] + w[2];
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w_2 = w[0];
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w_3 = w[0] + w[1];
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if (w[1] == 0 || w[2] > 2 || w_total > sizeof(buffer))
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{
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_pdfioFileError(pdf, "Cross-reference stream has invalid W key.");
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return (false);
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}
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if ((st = pdfioObjOpenStream(obj, true)) == NULL)
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{
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_pdfioFileError(pdf, "Unable to open cross-reference stream.");
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return (false);
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}
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while (pdfioStreamRead(st, buffer, w_total) > 0)
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{
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PDFIO_DEBUG("load_xref: %02X%02X%02X%02X%02X\n", buffer[0], buffer[1], buffer[2], buffer[3], buffer[4]);
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// Check whether this is an object definition...
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if (w[0] > 0)
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{
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if (buffer[0] == 0)
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{
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// Ignore free objects...
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continue;
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}
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else if (buffer[0] == 2)
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{
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// TODO: Add support for compressed object streams...
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// Compressed object...
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_pdfioFileError(pdf, "PDF file contains compressed object streams which are not currently supported.");
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continue;
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}
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}
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for (i = 1, offset = buffer[w_2]; i < w[1]; i ++)
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offset = (offset << 8) | buffer[w_2 + i];
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switch (w[2])
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{
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default :
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generation = 0;
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break;
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case 1 :
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generation = buffer[w_3];
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break;
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case 2 :
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generation = (buffer[w_3] << 8) | buffer[w_3 + 1];
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break;
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}
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// Create a placeholder for the object in memory...
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if (pdfioFileFindObject(pdf, (size_t)number))
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continue; // Don't replace newer object...
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if (!add_obj(pdf, (size_t)number, (unsigned short)generation, offset))
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return (false);
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}
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pdfioStreamClose(st);
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}
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else if (!strcmp(line, "xref"))
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{
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@ -200,9 +200,21 @@ pdfio_stream_t * // O - Stream or `NULL` on error
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pdfioObjOpenStream(pdfio_obj_t *obj, // I - Object
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bool decode) // I - Decode/decompress data?
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{
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// TODO: Implement me
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(void)obj;
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(void)decode;
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// Range check input...
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if (!obj)
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return (NULL);
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return (NULL);
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// Make sure we've loaded the object dictionary...
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if (!obj->value.type)
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{
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if (!_pdfioObjLoad(obj))
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return (NULL);
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}
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// No stream if there is no dict or offset to a stream...
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if (obj->value.type != PDFIO_VALTYPE_DICT || !obj->stream_offset)
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return (NULL);
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// Open the stream...
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return (_pdfioStreamOpen(obj, decode));
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}
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@ -69,6 +69,17 @@ typedef enum _pdfio_mode_e // Read/write mode
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_PDFIO_MODE_WRITE // Write a PDF file
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} _pdfio_mode_t;
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typedef enum _pdfio_predictor_e // PNG predictor constants
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{
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_PDFIO_PREDICTOR_NONE = 1, // No predictor (default)
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_PDFIO_PREDICTOR_TIFF2 = 2, // TIFF2 predictor (???)
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_PDFIO_PREDICTOR_PNG_NONE = 10, // PNG None predictor (same as `_PDFIO_PREDICTOR_NONE`)
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_PDFIO_PREDICTOR_PNG_SUB = 11, // PNG Sub predictor
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_PDFIO_PREDICTOR_PNG_UP = 12, // PNG Up predictor
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_PDFIO_PREDICTOR_PNG_AVERAGE = 13, // PNG Average predictor
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_PDFIO_PREDICTOR_PNG_PAETH = 14 // PNG Paeth predictor
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} _pdfio_predictor_t;
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typedef struct _pdfio_value_s // Value structure
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{
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pdfio_valtype_t type; // Type of value
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@ -174,9 +185,12 @@ struct _pdfio_stream_s // Stream
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pdfio_file_t *pdf; // PDF file
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pdfio_obj_t *obj; // Object
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pdfio_filter_t filter; // Compression/decompression filter
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char buffer[8192]; // Read/write buffer
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size_t bufused; // Number of bytes in buffer
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size_t remaining; // Remaining bytes in stream
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char buffer[8192], // Read/write buffer
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*bufptr, // Current position in buffer
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*bufend; // End of buffer
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z_stream flate; // Flate filter state
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char cbuffer[4096]; // Compressed data buffer
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};
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typedef ssize_t (*_pdfio_tconsume_cb_t)(void *data, size_t bytes);
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249
pdfio-stream.c
249
pdfio-stream.c
@ -14,6 +14,13 @@
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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 ssize_t stream_read(pdfio_stream_t *st, char *buffer, size_t bytes);
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//
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// 'pdfioStreamClose()' - Close a (data) stream in a PDF file.
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//
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@ -54,10 +61,35 @@ bool // O - `true` on success, `false` on EOF
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pdfioStreamConsume(pdfio_stream_t *st, // I - Stream
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size_t bytes)// I - Number of bytes to consume
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{
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// TODO: Implement me
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(void)st;
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(void)bytes;
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return (false);
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size_t remaining; // Remaining bytes in buffer
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ssize_t rbytes; // Bytes read
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// Range check input...
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if (!st || st->pdf->mode != _PDFIO_MODE_READ || !bytes)
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return (false);
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// Skip bytes in the stream buffer until we've consumed the requested number
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// or get to the end of the stream...
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while ((remaining = (size_t)(st->bufend - st->bufptr)) < bytes)
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{
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bytes -= remaining;
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if ((rbytes = stream_read(st, st->buffer, sizeof(st->buffer))) > 0)
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{
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st->bufptr = st->buffer;
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st->bufend = st->buffer + rbytes;
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}
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else
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{
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st->bufptr = st->bufend = st->buffer;
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return (false);
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}
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}
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st->bufptr += bytes;
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return (true);
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}
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@ -107,6 +139,9 @@ _pdfioStreamOpen(pdfio_obj_t *obj, // I - Object
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bool decode) // I - Decode/decompress the stream?
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{
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pdfio_stream_t *st; // Stream
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pdfio_dict_t *dict = pdfioObjGetDict(obj);
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// Object dictionary
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size_t length; // Length of stream
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// Allocate a new stream object...
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@ -121,11 +156,36 @@ _pdfioStreamOpen(pdfio_obj_t *obj, // I - Object
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_pdfioFileSeek(st->pdf, obj->stream_offset, SEEK_SET);
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if ((length = (size_t)pdfioDictGetNumber(dict, "Length")) == 0)
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{
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// Length must be an indirect reference...
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pdfio_obj_t *lenobj; // Length object
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if ((lenobj = pdfioDictGetObject(dict, "Length")) == NULL)
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{
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_pdfioFileError(obj->pdf, "Unable to get length of stream.");
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free(st);
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return (NULL);
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}
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if (lenobj->value.type == PDFIO_VALTYPE_NONE)
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_pdfioObjLoad(lenobj);
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if (lenobj->value.type != PDFIO_VALTYPE_NUMBER || lenobj->value.value.number <= 0.0f)
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{
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_pdfioFileError(obj->pdf, "Unable to get length of stream.");
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free(st);
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return (NULL);
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}
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length = (size_t)lenobj->value.value.number;
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}
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st->remaining = length;
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if (decode)
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{
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// Try to decode/decompress the contents of this object...
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pdfio_dict_t *dict = pdfioObjGetDict(obj);
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// Object dictionary
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const char *filter = pdfioDictGetName(dict, "Filter");
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// Filter value
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@ -146,6 +206,7 @@ _pdfioStreamOpen(pdfio_obj_t *obj, // I - Object
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else if (!strcmp(filter, "FlateDecode"))
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{
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// Flate compression
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#if 0 // TODO: Determine whether we need to implement support for predictors
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int bpc = (int)pdfioDictGetNumber(dict, "BitsPerComponent");
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// Bits per component
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int colors = (int)pdfioDictGetNumber(dict, "Colors");
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@ -154,8 +215,26 @@ _pdfioStreamOpen(pdfio_obj_t *obj, // I - Object
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// Number of columns
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int predictor = (int)pdfioDictGetNumber(dict, "Predictor");
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// Predictory value, if any
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#endif // 0
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st->filter = PDFIO_FILTER_FLATE;
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st->flate.zalloc = (alloc_func)0;
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st->flate.zfree = (free_func)0;
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st->flate.opaque = (voidpf)0;
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st->flate.next_in = (Bytef *)st->cbuffer;
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st->flate.next_out = NULL;
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st->flate.avail_in = (uInt)_pdfioFileRead(st->pdf, st->cbuffer, sizeof(st->cbuffer));
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st->flate.avail_out = 0;
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if (inflateInit(&(st->flate)) != Z_OK)
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{
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_pdfioFileError(st->pdf, "Unable to start Flate filter.");
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free(st);
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return (NULL);
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}
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st->remaining -= st->flate.avail_in;
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}
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else if (!strcmp(filter, "LZWDecode"))
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{
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@ -189,12 +268,40 @@ pdfioStreamPeek(pdfio_stream_t *st, // I - Stream
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void *buffer, // I - Buffer
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size_t bytes) // I - Size of buffer
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{
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// TODO: Implement me
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(void)st;
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(void)buffer;
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(void)bytes;
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size_t remaining; // Remaining bytes in buffer
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return (-1);
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// Range check input...
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if (!st || st->pdf->mode != _PDFIO_MODE_READ || !buffer || !bytes)
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return (-1);
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// See if we have enough bytes in the buffer...
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if ((remaining = (size_t)(st->bufend - st->bufptr)) < bytes)
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{
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// No, shift the buffer and read more
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ssize_t rbytes; // Bytes read
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if (remaining > 0)
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memmove(st->buffer, st->bufptr, remaining);
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st->bufptr = st->buffer;
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st->bufend = st->buffer + remaining;
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if ((rbytes = stream_read(st, st->bufptr, sizeof(st->buffer) - remaining)) > 0)
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{
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st->bufend += rbytes;
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remaining += (size_t)rbytes;
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}
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}
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// Copy bytes from the buffer...
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if (bytes > remaining)
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bytes = remaining;
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memcpy(buffer, st->bufptr, bytes);
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// Return the number of bytes that were copied...
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return ((ssize_t)bytes);
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}
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@ -247,12 +354,57 @@ pdfioStreamRead(
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void *buffer, // I - Buffer
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size_t bytes) // I - Bytes to read
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{
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// TODO: Implement me
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(void)st;
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(void)buffer;
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(void)bytes;
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char *bufptr = (char *)buffer;
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// Pointer into buffer
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size_t remaining; // Remaining bytes in buffer
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ssize_t rbytes; // Bytes read
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return (-1);
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// Range check input...
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if (!st || st->pdf->mode != _PDFIO_MODE_READ || !buffer || !bytes)
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return (-1);
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// Loop until we have the requested bytes or hit the end of the stream...
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while ((remaining = (size_t)(st->bufend - st->bufptr)) < bytes)
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{
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memcpy(bufptr, st->bufptr, remaining);
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bufptr += remaining;
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bytes -= remaining;
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if (bytes >= sizeof(st->buffer))
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{
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// Read large amounts directly to caller's buffer...
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if ((rbytes = stream_read(st, bufptr, bytes)) > 0)
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{
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bufptr += rbytes;
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bytes = 0;
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}
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st->bufptr = st->bufend = st->buffer;
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break;
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}
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else if ((rbytes = stream_read(st, st->buffer, sizeof(st->buffer))) > 0)
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{
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st->bufptr = st->buffer;
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st->bufend = st->buffer + rbytes;
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}
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else
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{
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st->bufptr = st->bufend = st->buffer;
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break;
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}
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}
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// Copy any remaining bytes from the stream buffer...
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if (bytes > 0)
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{
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memcpy(bufptr, st->bufptr, bytes);
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bufptr += bytes;
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st->bufptr += bytes;
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}
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// Return the number of bytes that were read...
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return (bufptr - (char *)buffer);
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}
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@ -273,3 +425,68 @@ pdfioStreamWrite(
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return (false);
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}
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//
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// 'stream_read()' - Read data from a stream, including filters.
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//
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static ssize_t // O - Number of bytes read or `-1` on error
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stream_read(pdfio_stream_t *st, // I - Stream
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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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if (st->filter == PDFIO_FILTER_NONE)
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{
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// No filtering, but limit reads to the length of the stream...
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if (bytes > st->remaining)
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rbytes = _pdfioFileRead(st->pdf, buffer, st->remaining);
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else
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rbytes = _pdfioFileRead(st->pdf, buffer, bytes);
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if (rbytes > 0)
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st->remaining -= (size_t)rbytes;
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return (rbytes);
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}
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else if (st->filter == PDFIO_FILTER_FLATE)
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{
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// Deflate compression...
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int status; // Status of decompression
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if (st->flate.avail_in == 0)
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{
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// Read more from the file...
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if (sizeof(st->cbuffer) > st->remaining)
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rbytes = _pdfioFileRead(st->pdf, st->cbuffer, st->remaining);
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||||
else
|
||||
rbytes = _pdfioFileRead(st->pdf, st->cbuffer, sizeof(st->cbuffer));
|
||||
|
||||
if (rbytes <= 0)
|
||||
return (-1); // End of file...
|
||||
|
||||
st->remaining -= (size_t)rbytes;
|
||||
st->flate.next_in = (Bytef *)st->cbuffer;
|
||||
st->flate.avail_in = (uInt)rbytes;
|
||||
}
|
||||
|
||||
// Decompress into the buffer...
|
||||
st->flate.next_out = (Bytef *)buffer;
|
||||
st->flate.avail_out = (uInt)bytes;
|
||||
|
||||
if ((status = inflate(&(st->flate), Z_NO_FLUSH)) < Z_OK)
|
||||
{
|
||||
_pdfioFileError(st->pdf, "Unable to decompress stream data: %d", status);
|
||||
return (-1);
|
||||
}
|
||||
|
||||
return (st->flate.next_out - (Bytef *)buffer);
|
||||
}
|
||||
|
||||
// If we get here something bad happened...
|
||||
return (-1);
|
||||
}
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user