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Added a few helper functions

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- open_stream_ext: opens a streamfile based on the filename + ext
- find_chunk_be/le: finds chunk_offset in chunked headers
This commit is contained in:
bnnm 2017-01-14 01:37:53 +01:00
parent afed5c2e15
commit 48fa7b7dc0
2 changed files with 58 additions and 0 deletions
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53
src/streamfile.c
View File

@ -273,6 +273,18 @@ size_t get_streamfile_dos_line(int dst_length, char * dst, off_t offset,
}
/**
* Opens an stream using the base streamFile name plus a new extension (ex. for headers in a separate file)
*/
STREAMFILE * open_stream_ext(STREAMFILE *streamFile, const char * ext) {
char filename_ext[PATH_LIMIT];
streamFile->get_name(streamFile,filename_ext,sizeof(filename_ext));
strcpy(filename_ext + strlen(filename_ext) - strlen(filename_extension(filename_ext)), ext);
return streamFile->open(streamFile,filename_ext,STREAMFILE_DEFAULT_BUFFER_SIZE);
}
/**
* open file containing decryption keys and copy to buffer
* tries combinations of keynames based on the original filename
@ -419,3 +431,44 @@ int check_extensions(STREAMFILE *streamFile, const char * cmp_exts) {
return 0;
}
/**
* Find a chunk starting from an offset, and save its offset/size (if not NULL), with offset after id/size.
* Works for chunked headers in the form of "chunk_id chunk_size (data)"xN (ex. RIFF).
* The start_offset should be the first actual chunk (not "RIFF" or "WAVE" but "fmt ").
* "full_chunk_size" signals chunk_size includes 4+4+data.
*
* returns 0 on failure
*/
static int find_chunk(STREAMFILE *streamFile, uint32_t chunk_id, off_t start_offset, int full_chunk_size, int size_big_endian, off_t *out_chunk_offset, size_t *out_chunk_size);
int find_chunk_be(STREAMFILE *streamFile, uint32_t chunk_id, off_t start_offset, int full_chunk_size, off_t *out_chunk_offset, size_t *out_chunk_size) {
return find_chunk(streamFile, chunk_id, start_offset, full_chunk_size, 1, out_chunk_offset, out_chunk_size);
}
int find_chunk_le(STREAMFILE *streamFile, uint32_t chunk_id, off_t start_offset, int full_chunk_size, off_t *out_chunk_offset, size_t *out_chunk_size) {
return find_chunk(streamFile, chunk_id, start_offset, full_chunk_size, 0, out_chunk_offset, out_chunk_size);
}
int find_chunk(STREAMFILE *streamFile, uint32_t chunk_id, off_t start_offset, int full_chunk_size, int size_big_endian, off_t *out_chunk_offset, size_t *out_chunk_size) {
size_t filesize;
off_t current_chunk = start_offset;
filesize = get_streamfile_size(streamFile);
/* read chunks */
while (current_chunk < filesize) {
uint32_t chunk_type = read_32bitBE(current_chunk,streamFile);
off_t chunk_size = size_big_endian ?
read_32bitBE(current_chunk+4,streamFile) :
read_32bitLE(current_chunk+4,streamFile);
if (chunk_type == chunk_id) {
if (out_chunk_offset) *out_chunk_offset = current_chunk+8;
if (out_chunk_size) *out_chunk_size = chunk_size;
return 1;
}
current_chunk += full_chunk_size ? chunk_size : 4+4+chunk_size;
}
return 0;
}

5
src/streamfile.h
View File

@ -148,10 +148,15 @@ static inline STREAMFILE * open_stdio_streamfile(const char * const filename) {
size_t get_streamfile_dos_line(int dst_length, char * dst, off_t offset, STREAMFILE * infile, int *line_done_ptr);
STREAMFILE * open_stream_ext(STREAMFILE *streamFile, const char * ext);
int read_key_file(uint8_t * buf, size_t bufsize, STREAMFILE *streamFile);
int read_pos_file(uint8_t * buf, size_t bufsize, STREAMFILE *streamFile);
int check_extensions(STREAMFILE *streamFile, const char * cmp_exts);
int find_chunk_be(STREAMFILE *streamFile, uint32_t chunk_id, off_t start_offset, int full_chunk_size, off_t *out_chunk_offset, size_t *out_chunk_size);
int find_chunk_le(STREAMFILE *streamFile, uint32_t chunk_id, off_t start_offset, int full_chunk_size, off_t *out_chunk_offset, size_t *out_chunk_size);
#endif