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Rework object and xref processing to allow for sparse object lists and generation numbers.

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This commit is contained in:
Michael R Sweet
2021-05-04 16:06:14 -04:00
parent 6287ede911
commit 7733fbeb10
4 changed files with 81 additions and 17 deletions
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78
pdfio-file.c
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@@ -21,7 +21,8 @@
// Local functions...
//
static pdfio_obj_t *add_object(pdfio_file_t *pdf);
static pdfio_obj_t *add_obj(pdfio_file_t *pdf, size_t number, unsigned short generation, off_t offset);
static int compare_objs(pdfio_obj_t **a, pdfio_obj_t **b);
static bool load_xref(pdfio_file_t *pdf, off_t xref_offset);
static bool write_trailer(pdfio_file_t *pdf);
@@ -221,6 +222,34 @@ pdfioFileCreatePage(pdfio_file_t *pdf, // I - PDF file
}
//
// 'pdfioFileFindObject()' - Find an object using its object number.
//
// This differs from @link pdfioFileGetObject@ which takes an index into the
// list of objects while this function takes the object number.
//
pdfio_obj_t * // O - Object or `NULL` if not found
pdfioFileFindObject(
pdfio_file_t *pdf, // I - PDF file
size_t number) // I - Object number (1 to N)
{
pdfio_obj_t key, // Search key
*keyptr; // Pointer to key
if (pdf->num_objs > 0)
{
key.number = number;
keyptr = &key;
return ((pdfio_obj_t *)bsearch(&keyptr, pdf->objs, pdf->num_objs, sizeof(pdfio_obj_t *), (int (*)(const void *, const void *))compare_objs));
}
return (NULL);
}
//
// 'pdfioFileGetID()' - Get the PDF file's ID strings.
//
@@ -407,13 +436,16 @@ pdfioFileOpen(
//
// 'add_object()' - Add an object to a PDF file.
// '_pdfioObjAdd()' - Add an object to a file.
//
static pdfio_obj_t * // O - New object
add_object(pdfio_file_t *pdf) // I - PDF file
pdfio_obj_t * // O - Object
add_obj(pdfio_file_t *pdf, // I - PDF file
size_t number, // I - Object number
unsigned short generation, // I - Object generation
off_t offset) // I - Offset in file
{
pdfio_obj_t *obj; // New object
pdfio_obj_t *obj; // Object
// Allocate memory for the object...
@@ -441,7 +473,33 @@ add_object(pdfio_file_t *pdf) // I - PDF file
pdf->objs[pdf->num_objs ++] = obj;
obj->number = number;
obj->generation = generation;
obj->offset = offset;
// Re-sort object array as needed...
if (pdf->num_objs > 1 && pdf->objs[pdf->num_objs - 2]->number > number)
qsort(pdf->objs, pdf->num_objs, sizeof(pdfio_obj_t *), (int (*)(const void *, const void *))compare_objs);
return (obj);
}
//
// 'compare_objs()' - Compare the object numbers of two objects.
//
static int
compare_objs(pdfio_obj_t **a, // I - First object
pdfio_obj_t **b) // I - Second object
{
if ((*a)->number < (*b)->number)
return (-1);
else if ((*a)->number == (*b)->number)
return (0);
else
return (1);
}
@@ -499,7 +557,6 @@ load_xref(pdfio_file_t *pdf, // I - PDF file
{
intmax_t offset; // Offset in file
int generation; // Generation number
pdfio_obj_t *obj; // Object
// Read a line from the file and validate it...
if (_pdfioFileRead(pdf, line, 20) != 20)
@@ -544,12 +601,11 @@ load_xref(pdfio_file_t *pdf, // I - PDF file
continue; // Don't care about free objects...
// Create a placeholder for the object in memory...
if ((obj = add_object(pdf)) == NULL)
return (false);
if (pdfioFileFindObject(pdf, (size_t)number))
continue; // Don't replace newer object...
obj->number = (size_t)number;
obj->generation = (unsigned short)generation;
obj->offset = offset;
if (!add_obj(pdf, (size_t)number, (unsigned short)generation, offset))
return (false);
}
}