mirror of
https://github.com/panzi/mediaextract
synced 2025-02-17 13:07:24 +00:00
better error handling
This commit is contained in:
Mathias Panzenböck
parent
5e7b48f2f9
commit
6fc0b55c9a
9
Makefile
Normal file
9
Makefile
Normal file
@ -0,0 +1,9 @@
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.PHONY: all clean
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all: oggextract
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oggextract: oggextract.c
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gcc -Wall -std=c99 -O2 $< -o $@
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clean:
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rm oggextract
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262
oggextract.c
262
oggextract.c
@ -15,160 +15,240 @@
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#include <sys/stat.h>
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#include <sys/mman.h>
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#define OGG_HEADER_SIZE 27
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#define ogg_isinitial(data) ((data)[5] & 2)
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int usage()
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{
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fprintf(stderr, "Usage: oggextract <filename> [<filename> ...]");
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fprintf(stderr, "Usage: oggextract <filename> [<filename> ...]\n");
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return 255;
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}
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int findpattern(unsigned char *data, int datalen, int start)
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const unsigned char *findpattern(const unsigned char *start, const unsigned char *end)
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{
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int i;
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end -= 4;
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for (; start < end; ++ start)
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{
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if (*(const int *)start == 0x5367674f) /* "OggS" */
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return start;
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}
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for (i = start; i < datalen - 4; i++)
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if (*(int *)(data + i) == 0x5367674f) /* "OggS" */
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return i;
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return -1;
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return NULL;
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}
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int ogg_ispage(unsigned char *data)
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int ogg_ispage(const unsigned char *start, const unsigned char *end, size_t *lengthptr)
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{
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unsigned char nsegs;
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size_t length, i;
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const unsigned char *segs = start + OGG_HEADER_SIZE;
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/* full header available? */
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if (end <= (unsigned char*)OGG_HEADER_SIZE || end - OGG_HEADER_SIZE < start)
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return 0;
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/* capture pattern */
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if (*(int *)data != 0x5367674f) /* "OggS" */
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if (*(const int *)start != 0x5367674f) /* "OggS" */
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return 0;
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/* stream structure version */
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if (data[4] != 0x00)
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if (start[4] != 0x00)
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return 0;
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/* header type flag */
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if ((data[5] & ~7) != 0x00)
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if ((start[5] & ~7) != 0x00)
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return 0;
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nsegs = start[26];
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length = OGG_HEADER_SIZE + nsegs;
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/* segment sizes fully available? */
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if (end <= (unsigned char*)length || end - length < start)
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return 0;
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for (i = 0; i < nsegs; ++ i)
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{
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length += segs[i];
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}
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/* segments fully available? */
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if (end <= (unsigned char*)length || end - length < start)
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return 0;
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if (lengthptr)
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*lengthptr = length;
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/* I think we can reasonably assume it is a real page now */
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return 1;
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}
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unsigned int ogg_getlength(unsigned char *data)
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unsigned int ogg_getlength(const unsigned char *data)
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{
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unsigned char nsegs;
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unsigned char *segs;
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unsigned char nsegs = data[26];
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const unsigned char *segs = data + 27;
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int length = 27 + nsegs;
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int i;
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int length;
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nsegs = data[26];
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segs = data + 27;
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length = 27 + nsegs;
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for (i = 0; i < nsegs; i++)
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length += segs[i];
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return length;
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}
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int ogg_isinitial(unsigned char *data)
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const char *basename(const char *path)
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{
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return data[5] & 2;
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const char *ptr = strrchr(path, '/');
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#if defined(_WIN16) || defined(_WIN32) || defined(_WIN64)
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/* Windows supports both / and \ */
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const char *ptr2 = strtchr(path, '\\');
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if (ptr2 > ptr)
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ptr = ptr2;
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#endif
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return ptr ? ptr + 1 : path;
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}
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int ogg_isfinal(unsigned char *data)
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int extract(const char *filepath, size_t *numfilesptr)
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{
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return data[5] & 4;
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}
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int extract(char *filename)
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{
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int fd;
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int fd = -1;
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struct stat statdata;
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int filesize;
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unsigned char *filedata, *oggdata;
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size_t filesize = 0;
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unsigned char *filedata = NULL;
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const unsigned char *ptr = NULL, *end = NULL;
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int pos = 0;
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int pagelen;
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size_t pagelen = 0;
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int outfd = -1;
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char *outfilename;
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int success = 1;
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char *outfilename = NULL;
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int numfiles = 0;
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size_t numfiles = 0;
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const char *filename = basename(filepath);
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size_t namelen = strlen(filename) + 16;
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printf("Extracting %s...\n", filename);
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if (stat(filename, &statdata) < 0)
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{
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perror("stat");
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return 1;
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}
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if (statdata.st_mode & S_IFDIR)
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{
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fprintf(stderr, "error: Is a directory\n", filename);
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return 1;
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}
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filesize = statdata.st_size;
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printf("Extracting %s\n", filepath);
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/* FIXME: prone to race conditions */
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fd = open(filename, O_RDONLY);
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fd = open(filepath, O_RDONLY);
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if (fd < 0)
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{
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perror("open");
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return 1;
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success = 0;
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goto exit_numfiles;
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}
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if (fstat(fd, &statdata) < 0)
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{
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perror("stat");
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success = 0;
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goto exit_fd;
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}
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if (S_ISDIR(statdata.st_mode))
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{
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fprintf(stderr, "error: Is a directory: %s\n", filepath);
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success = 0;
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goto exit_fd;
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}
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filesize = statdata.st_size;
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filedata = mmap(0, filesize, PROT_READ, MAP_PRIVATE, fd, 0);
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outfilename = malloc(strlen(filename) + 16);
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while (1)
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{
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pos = findpattern(filedata, filesize, pos);
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if (pos < 0)
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break;
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oggdata = filedata + pos;
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if (ogg_ispage(oggdata))
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{
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pagelen = ogg_getlength(oggdata);
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if (outfd < 0 && ogg_isinitial(oggdata))
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{
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sprintf(outfilename, "%s_%08x.ogg", filename, pos);
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outfd = creat(outfilename, -1);
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numfiles++;
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}
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if (outfd >= 0)
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{
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write(outfd, oggdata, pagelen);
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if (ogg_isfinal(oggdata))
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{
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close(outfd);
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outfd = -1;
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}
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}
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}
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pos += pagelen;
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if (filedata == MAP_FAILED) {
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perror("mmap");
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success = 0;
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goto exit_fd;
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}
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if (outfd != -1 && ogg_isfinal(oggdata))
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outfilename = malloc(namelen);
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if (outfilename == NULL) {
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perror("malloc");
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success = 0;
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goto exit_munmap;
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}
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ptr = filedata;
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for (end = filedata + filesize; (ptr = findpattern(ptr, end));)
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{
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if (ogg_ispage(ptr, end, &pagelen) && (outfd >= 0 || ogg_isinitial(ptr)))
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{
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pagelen = ogg_getlength(ptr);
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if (outfd < 0)
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{
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snprintf(outfilename, namelen, "%s_%08x.ogg", filename, (unsigned int)(ptr - filedata));
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outfd = creat(outfilename, -1);
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if (outfd < 0)
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{
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perror("creat");
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success = 0;
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goto exit_free;
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}
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printf("writing file: %s\n", outfilename);
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++ numfiles;
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}
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if (write(outfd, ptr, pagelen) < 0)
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{
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perror("write");
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success = 0;
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goto exit_outfd;
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}
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ptr += pagelen;
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}
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else
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{
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if (outfd >= 0)
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{
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close(outfd);
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outfd = -1;
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}
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ptr += 4;
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}
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}
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exit_outfd:
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if (outfd >= 0)
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close(outfd);
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exit_free:
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free(outfilename);
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exit_munmap:
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munmap(filedata, filesize);
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exit_fd:
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close(fd);
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printf("%d file(s) written.\n", numfiles);
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exit_numfiles:
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if (numfilesptr)
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*numfilesptr = numfiles;
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return 0;
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return success;
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}
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int main(int argc, char **argv)
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{
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int i;
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int failures;
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int i = 0;
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size_t failures = 0;
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size_t sumnumfiles = 0;
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size_t numfiles = 0;
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if (argc < 2)
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return usage();
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failures = 0;
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for (i = 1; i < argc; i++)
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failures += extract(argv[i]);
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for (i = 1; i < argc; ++i)
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{
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if (extract(argv[i], &numfiles))
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{
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sumnumfiles += numfiles;
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}
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else {
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fprintf(stderr, "Error processing file: %s\n", argv[i]);
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failures += 1;
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}
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}
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printf("Extracted %lu file(s).\n", numfiles);
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if (failures > 0)
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fprintf(stderr, "Errors processing %d file(s).\n", failures);
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{
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fprintf(stderr, "%lu error(s) during extraction.\n", failures);
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return 1;
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}
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return 0;
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}
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