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Backport reading improvements/bug fixes from master.

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This commit is contained in:
Michael R Sweet
2025-04-24 12:19:11 -04:00
parent f9c07a0346
commit 8f706b9fe7
5 changed files with 175 additions and 100 deletions
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241
pdfio-file.c
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@@ -1049,7 +1049,7 @@ pdfioFileOpen(
}
// Read the header from the first line...
if (!_pdfioFileGets(pdf, line, sizeof(line)))
if (!_pdfioFileGets(pdf, line, sizeof(line), true))
goto error;
if ((strncmp(line, "%PDF-1.", 7) && strncmp(line, "%PDF-2.", 7)) || !isdigit(line[7] & 255))
@@ -1063,7 +1063,7 @@ pdfioFileOpen(
pdf->version = strdup(line + 5);
// Grab the last 1k of the file to find the start of the xref table...
if (_pdfioFileSeek(pdf, -1024, SEEK_END) < 0)
if (_pdfioFileSeek(pdf, 1 - sizeof(line), SEEK_END) < 0)
{
_pdfioFileError(pdf, "Unable to read startxref data.");
goto error;
@@ -1075,28 +1075,36 @@ pdfioFileOpen(
goto error;
}
PDFIO_DEBUG("pdfioOpen: Read %d bytes at end of file.\n", (int)bytes);
line[bytes] = '\0';
end = line + bytes - 9;
for (ptr = line; ptr < end; ptr ++)
{
if (!memcmp(ptr, "startxref", 9))
if (!strncmp(ptr, "startxref", 9) && !strstr(ptr + 9, "startxref") && strtol(ptr + 9, NULL, 10) > 0)
break;
}
if (ptr >= end)
{
_pdfioFileError(pdf, "Unable to find start of xref table.");
goto error;
}
if (!_pdfioFileError(pdf, "WARNING: Unable to find start of cross-reference table, will attempt to rebuild."))
goto error;
xref_offset = (off_t)strtol(ptr + 9, NULL, 10);
if (!load_xref(pdf, xref_offset, password_cb, password_cbdata))
{
if (!repair_xref(pdf, password_cb, password_cbdata))
goto error;
}
else
{
PDFIO_DEBUG("pdfioFileOpen: line=%p,ptr=%p(\"%s\")\n", line, ptr, ptr);
xref_offset = (off_t)strtol(ptr + 9, NULL, 10);
PDFIO_DEBUG("pdfioFileOpen: xref_offset=%lu\n", (unsigned long)xref_offset);
if (!load_xref(pdf, xref_offset, password_cb, password_cbdata))
goto error;
}
return (pdf);
@@ -1744,31 +1752,32 @@ load_xref(
int generation; // Generation number
_pdfio_token_t tb; // Token buffer/stack
off_t line_offset; // Offset to start of line
pdfio_obj_t *pages_obj; // Pages object
while (!done)
{
if (_pdfioFileSeek(pdf, xref_offset, SEEK_SET) != xref_offset)
{
_pdfioFileError(pdf, "Unable to seek to start of xref table.");
return (false);
PDFIO_DEBUG("load_xref: Unable to seek to %lu.\n", (unsigned long)xref_offset);
goto repair;
}
do
{
line_offset = _pdfioFileTell(pdf);
if (!_pdfioFileGets(pdf, line, sizeof(line)))
if (!_pdfioFileGets(pdf, line, sizeof(line), true))
{
_pdfioFileError(pdf, "Unable to read start of xref table.");
return (false);
PDFIO_DEBUG("load_xref: Unable to read line at offset %lu.\n", (unsigned long)line_offset);
goto repair;
}
}
while (!line[0]);
PDFIO_DEBUG("load_xref: line_offset=%lu, line='%s'\n", (unsigned long)line_offset, line);
if (isdigit(line[0] & 255) && strlen(line) > 4 && (!strcmp(line + strlen(line) - 4, " obj") || ((ptr = strstr(line, " obj")) != NULL && ptr[4] == '<')))
if (isdigit(line[0] & 255) && strlen(line) > 4 && (!strcmp(line + strlen(line) - 4, " obj") || ((ptr = strstr(line, " obj")) != NULL && (ptr[4] == '<' || isspace(ptr[4])))))
{
// Cross-reference stream
pdfio_obj_t *obj; // Object
@@ -1790,14 +1799,14 @@ load_xref(
if ((number = strtoimax(line, &ptr, 10)) < 1)
{
_pdfioFileError(pdf, "Bad xref table header '%s'.", line);
return (false);
PDFIO_DEBUG("load_xref: Unable to scan object number.\n");
goto repair;
}
if ((generation = (int)strtol(ptr, &ptr, 10)) < 0 || (generation > 65535 && number != 0))
{
_pdfioFileError(pdf, "Bad xref table header '%s'.", line);
return (false);
PDFIO_DEBUG("load_xref: Unable to scan generation number (%u).\n", (unsigned)generation);
goto repair;
}
while (isspace(*ptr & 255))
@@ -1805,14 +1814,14 @@ load_xref(
if (strncmp(ptr, "obj", 3))
{
_pdfioFileError(pdf, "Bad xref table header '%s'.", line);
return (false);
PDFIO_DEBUG("load_xref: No 'obj' after object number and generation (saw '%s').\n", ptr);
goto repair;
}
if (_pdfioFileSeek(pdf, line_offset + (off_t)(ptr + 3 - line), SEEK_SET) < 0)
{
_pdfioFileError(pdf, "Unable to seek to xref object %lu %u.", (unsigned long)number, (unsigned)generation);
return (false);
PDFIO_DEBUG("load_xref: Unable to seek to start of cross-reference object dictionary.\n");
goto repair;
}
PDFIO_DEBUG("load_xref: Loading object %lu %u.\n", (unsigned long)number, (unsigned)generation);
@@ -1827,21 +1836,21 @@ load_xref(
if (!_pdfioValueRead(pdf, obj, &tb, &trailer, 0))
{
_pdfioFileError(pdf, "Unable to read cross-reference stream dictionary.");
return (false);
PDFIO_DEBUG("load_xref: Unable to read cross-reference object dictionary.\n");
goto repair;
}
else if (trailer.type != PDFIO_VALTYPE_DICT)
{
_pdfioFileError(pdf, "Cross-reference stream does not have a dictionary.");
return (false);
PDFIO_DEBUG("load_xref: Expected dictionary for cross-reference object (type=%d).", trailer.type);
goto repair;
}
obj->value = trailer;
if (!_pdfioTokenGet(&tb, line, sizeof(line)) || strcmp(line, "stream"))
{
_pdfioFileError(pdf, "Unable to get stream after xref dictionary.");
return (false);
PDFIO_DEBUG("load_xref: No stream token after dictionary (got '%s').\n", line);
goto repair;
}
PDFIO_DEBUG("load_xref: tb.bufptr=%p, tb.bufend=%p, tb.bufptr[0]=0x%02x, tb.bufptr[0]=0x%02x\n", tb.bufptr, tb.bufend, tb.bufptr[0], tb.bufptr[1]);
@@ -1859,8 +1868,8 @@ load_xref(
if ((w_array = pdfioDictGetArray(trailer.value.dict, "W")) == NULL)
{
_pdfioFileError(pdf, "Cross-reference stream does not have required W key.");
return (false);
PDFIO_DEBUG("load_xref: Missing W array in cross-reference objection dictionary.\n");
goto repair;
}
w[0] = (size_t)pdfioArrayGetNumber(w_array, 0);
@@ -1870,16 +1879,16 @@ load_xref(
w_2 = w[0];
w_3 = w[0] + w[1];
if (w[1] == 0 || w[2] > 4 || w[0] > sizeof(buffer) || w[1] > sizeof(buffer) || w[2] > sizeof(buffer) || w_total > sizeof(buffer))
if (pdfioArrayGetSize(w_array) > 3 || w[1] == 0 || w[2] > 4 || w[0] > sizeof(buffer) || w[1] > sizeof(buffer) || w[2] > sizeof(buffer) || w_total > sizeof(buffer))
{
_pdfioFileError(pdf, "Cross-reference stream has invalid W key [%u %u %u].", (unsigned)w[0], (unsigned)w[1], (unsigned)w[2]);
return (false);
PDFIO_DEBUG("load_xref: Bad W array in cross-reference objection dictionary.\n");
goto repair;
}
if ((st = pdfioObjOpenStream(obj, true)) == NULL)
{
_pdfioFileError(pdf, "Unable to open cross-reference stream.");
return (false);
PDFIO_DEBUG("load_xref: Unable to open cross-reference stream.\n");
goto repair;
}
for (index_n = 0; index_n < index_count; index_n += 2)
@@ -1981,6 +1990,7 @@ load_xref(
else
{
_pdfioFileError(pdf, "Too many object streams.");
pdfioStreamClose(st);
return (false);
}
}
@@ -1989,7 +1999,10 @@ load_xref(
{
// Add this object...
if (!add_obj(pdf, (size_t)number, (unsigned short)generation, (off_t)offset))
{
pdfioStreamClose(st);
return (false);
}
}
number ++;
@@ -2037,7 +2050,7 @@ load_xref(
// Offset of current line
PDFIO_DEBUG("load_xref: Reading xref table starting at offset %lu\n", (unsigned long)trailer_offset);
while (_pdfioFileGets(pdf, line, sizeof(line)))
while (_pdfioFileGets(pdf, line, sizeof(line), false))
{
PDFIO_DEBUG("load_xref: '%s' at offset %lu\n", line, (unsigned long)trailer_offset);
@@ -2062,8 +2075,8 @@ load_xref(
if (sscanf(line, "%jd%jd", &number, &num_objects) != 2)
{
_pdfioFileError(pdf, "Malformed xref table section '%s'.", line);
return (false);
PDFIO_DEBUG("load_xref: Unable to scan START COUNT from line.\n");
goto repair;
}
// Read this group of objects...
@@ -2071,41 +2084,45 @@ load_xref(
{
// Read a line from the file and validate it...
if (_pdfioFileRead(pdf, line, 20) != 20)
return (false);
{
PDFIO_DEBUG("load_xref: Unable to read 20 byte xref record.\n");
goto repair;
}
line[20] = '\0';
if (strcmp(line + 18, "\r\n") && strcmp(line + 18, " \n") && strcmp(line + 18, " \r"))
if (strcmp(line + 18, "\r\n") && strcmp(line + 18, "\r\r") && strcmp(line + 18, " \n") && strcmp(line + 18, " \r"))
{
_pdfioFileError(pdf, "Malformed xref table entry '%s'.", line);
return (false);
PDFIO_DEBUG("load_xref: Bad end-of-line <%02X%02X>\n", line[18], line[19]);
goto repair;
}
line[18] = '\0';
// Parse the line
if ((offset = strtoimax(line, &ptr, 10)) < 0)
{
_pdfioFileError(pdf, "Malformed xref table entry '%s'.", line);
return (false);
PDFIO_DEBUG("load_xref: Unable to scan offset.\n");
goto repair;
}
if ((generation = (int)strtol(ptr, &ptr, 10)) < 0 || (generation > 65535 && offset != 0))
{
_pdfioFileError(pdf, "Malformed xref table entry '%s'.", line);
return (false);
PDFIO_DEBUG("load_xref: Unable to scan generation (%u).\n", (unsigned)generation);
goto repair;
}
if (*ptr != ' ')
{
_pdfioFileError(pdf, "Malformed xref table entry '%s'.", line);
return (false);
PDFIO_DEBUG("load_xref: Missing space before type.\n");
goto repair;
}
ptr ++;
if (*ptr != 'f' && *ptr != 'n')
{
_pdfioFileError(pdf, "Malformed xref table entry '%s'.", line);
return (false);
PDFIO_DEBUG("load_xref: Bad type '%c'.\n", *ptr);
goto repair;
}
if (*ptr == 'f')
@@ -2124,21 +2141,21 @@ load_xref(
if (strncmp(line, "trailer", 7))
{
_pdfioFileError(pdf, "Missing trailer.");
return (false);
PDFIO_DEBUG("load_xref: No trailer after xref table.\n");
goto repair;
}
_pdfioTokenInit(&tb, pdf, (_pdfio_tconsume_cb_t)_pdfioFileConsume, (_pdfio_tpeek_cb_t)_pdfioFilePeek, pdf);
if (!_pdfioValueRead(pdf, NULL, &tb, &trailer, 0))
{
_pdfioFileError(pdf, "Unable to read trailer dictionary.");
return (false);
PDFIO_DEBUG("load_xref: Unable to read trailer dictionary.\n");
goto repair;
}
else if (trailer.type != PDFIO_VALTYPE_DICT)
{
_pdfioFileError(pdf, "Trailer is not a dictionary.");
return (false);
PDFIO_DEBUG("load_xref: Trailer not a dictionary (type=%d).\n", trailer.type);
goto repair;
}
PDFIO_DEBUG("load_xref: Got trailer dict.\n");
@@ -2160,8 +2177,7 @@ load_xref(
}
else
{
_pdfioFileError(pdf, "Bad xref table header '%s'.", line);
return (false);
goto repair;
}
PDFIO_DEBUG("load_xref: Contents of trailer dictionary:\n");
@@ -2190,13 +2206,31 @@ load_xref(
if ((pdf->root_obj = pdfioDictGetObj(pdf->trailer_dict, "Root")) == NULL)
{
_pdfioFileError(pdf, "Missing Root object.");
return (false);
PDFIO_DEBUG("load_xref: Missing Root object.\n");
goto repair;
}
PDFIO_DEBUG("load_xref: Root=%p(%lu)\n", pdf->root_obj, (unsigned long)pdf->root_obj->number);
return (load_pages(pdf, pdfioDictGetObj(pdfioObjGetDict(pdf->root_obj), "Pages"), 0));
if ((pages_obj = pdfioDictGetObj(pdfioObjGetDict(pdf->root_obj), "Pages")) == NULL)
{
PDFIO_DEBUG("load_xref: Missing Pages object.\n");
goto repair;
}
PDFIO_DEBUG("load_xref: Pages=%p(%lu)\n", pdf->root_obj, (unsigned long)pdf->root_obj->number);
return (load_pages(pdf, pages_obj, 0));
// If we get here the cross-reference table is busted - try repairing if the
// error callback says to proceed...
repair:
if (_pdfioFileError(pdf, "WARNING: Cross-reference is damaged, will attempt to rebuild."))
return (repair_xref(pdf, password_cb, password_data));
else
return (false);
}
@@ -2210,7 +2244,7 @@ repair_xref(
pdfio_password_cb_t password_cb, // I - Password callback or `NULL` for none
void *password_data) // I - Password callback data, if any
{
char line[16384], // Line from file
char line[1024], // Line from file
*ptr; // Pointer into line
off_t line_offset; // Offset in file
intmax_t number; // Object number
@@ -2218,16 +2252,21 @@ repair_xref(
size_t i; // Looping var
size_t num_sobjs = 0; // Number of object streams
pdfio_obj_t *sobjs[16384]; // Object streams to load
pdfio_obj_t *pages_obj; // Pages object
// Let caller know something is wrong...
_pdfioFileError(pdf, "WARNING: Cross-reference table is damaged, attempting to rebuild.");
// Clear trailer data...
pdf->trailer_dict = NULL;
pdf->root_obj = NULL;
pdf->info_obj = NULL;
pdf->pages_obj = NULL;
pdf->encrypt_obj = NULL;
// Read from the beginning of the file, looking for
// Read from the beginning of the file, looking for objects...
if ((line_offset = _pdfioFileSeek(pdf, 0, SEEK_SET)) < 0)
return (false);
while (_pdfioFileGets(pdf, line, sizeof(line)))
while (_pdfioFileGets(pdf, line, sizeof(line), true))
{
// See if this is the start of an object...
if (line[0] >= '1' && line[0] <= '9')
@@ -2244,43 +2283,61 @@ repair_xref(
pdfio_obj_t *obj; // Object
_pdfio_token_t tb; // Token buffer/stack
PDFIO_DEBUG("OBJECT %ld %d at offset %ld\n", (long)number, generation, (long)line_offset);
PDFIO_DEBUG("repair_xref: OBJECT %ld %d at offset %ld\n", (long)number, generation, (long)line_offset);
if ((obj = add_obj(pdf, (size_t)number, (unsigned short)generation, line_offset)) == NULL)
if ((obj = pdfioFileFindObj(pdf, (size_t)number)) != NULL)
{
obj->offset = line_offset;
}
else if ((obj = add_obj(pdf, (size_t)number, (unsigned short)generation, line_offset)) == NULL)
{
_pdfioFileError(pdf, "Unable to allocate memory for object.");
return (false);
}
if (ptr[3])
{
// Probably the start of the object dictionary, rewind the file so
// we can read it...
_pdfioFileSeek(pdf, line_offset + (ptr - line + 3), SEEK_SET);
}
_pdfioTokenInit(&tb, pdf, (_pdfio_tconsume_cb_t)_pdfioFileConsume, (_pdfio_tpeek_cb_t)_pdfioFilePeek, pdf);
if (!_pdfioValueRead(pdf, obj, &tb, &obj->value, 0))
{
_pdfioFileError(pdf, "Unable to read cross-reference stream dictionary.");
return (false);
if (!_pdfioFileError(pdf, "WARNING: Unable to read object dictionary/value."))
return (false);
else
continue;
}
if (_pdfioTokenGet(&tb, line, sizeof(line)) && strcmp(line, "stream"))
if (_pdfioTokenGet(&tb, line, sizeof(line)))
{
const char *type = pdfioObjGetType(obj);
// Object type
_pdfioTokenFlush(&tb);
obj->stream_offset = _pdfioFileTell(pdf);
if (type && !strcmp(type, "ObjStm") && num_sobjs < (sizeof(sobjs) / sizeof(sobjs[0])))
if (type && !strcmp(line, "stream"))
{
sobjs[num_sobjs] = obj;
num_sobjs ++;
}
// Possible object or XRef stream...
obj->stream_offset = _pdfioFileTell(pdf);
if (type && !strcmp(type, "XRef") && !pdf->trailer_dict)
{
// Save the trailer dictionary...
pdf->trailer_dict = pdfioObjGetDict(obj);
pdf->encrypt_obj = pdfioDictGetObj(pdf->trailer_dict, "Encrypt");
pdf->id_array = pdfioDictGetArray(pdf->trailer_dict, "ID");
}
if (!strcmp(type, "ObjStm") && num_sobjs < (sizeof(sobjs) / sizeof(sobjs[0])))
{
sobjs[num_sobjs] = obj;
num_sobjs ++;
}
if (!strcmp(type, "XRef") && !pdf->trailer_dict)
{
// Save the trailer dictionary...
pdf->trailer_dict = pdfioObjGetDict(obj);
pdf->encrypt_obj = pdfioDictGetObj(pdf->trailer_dict, "Encrypt");
pdf->id_array = pdfioDictGetArray(pdf->trailer_dict, "ID");
}
}
}
}
}
@@ -2298,7 +2355,7 @@ repair_xref(
_pdfioFileSeek(pdf, line_offset + 7, SEEK_SET);
}
PDFIO_DEBUG("TRAILER at offset %ld\n", (long)line_offset);
PDFIO_DEBUG("repair_xref: TRAILER at offset %ld\n", (long)line_offset);
_pdfioTokenInit(&tb, pdf, (_pdfio_tconsume_cb_t)_pdfioFileConsume, (_pdfio_tpeek_cb_t)_pdfioFilePeek, pdf);
if (!_pdfioValueRead(pdf, NULL, &tb, &trailer, 0))
@@ -2314,7 +2371,7 @@ repair_xref(
_pdfioTokenFlush(&tb);
if (!pdf->trailer_dict)
if (_pdfioDictGetValue(trailer.value.dict, "Root"))
{
// Save the trailer dictionary and grab the root (catalog) and info
// objects...
@@ -2351,8 +2408,16 @@ repair_xref(
PDFIO_DEBUG("repair_xref: Root=%p(%lu)\n", pdf->root_obj, (unsigned long)pdf->root_obj->number);
if ((pages_obj = pdfioDictGetObj(pdfioObjGetDict(pdf->root_obj), "Pages")) == NULL)
{
_pdfioFileError(pdf, "Missing Pages object.");
return (false);
}
PDFIO_DEBUG("repair_xref: Pages=%p(%lu)\n", pages_obj, (unsigned long)pages_obj->number);
// Load pages...
return (load_pages(pdf, pdfioDictGetObj(pdfioObjGetDict(pdf->root_obj), "Pages"), 0));
return (load_pages(pdf, pages_obj, 0));
}