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Diffstat (limited to 'Utilities/cmlibarchive/contrib/untar.c')
| -rw-r--r-- | Utilities/cmlibarchive/contrib/untar.c | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/Utilities/cmlibarchive/contrib/untar.c b/Utilities/cmlibarchive/contrib/untar.c new file mode 100644 index 0000000..0ea6455 --- /dev/null +++ b/Utilities/cmlibarchive/contrib/untar.c @@ -0,0 +1,225 @@ +/* + * "untar" is an extremely simple tar extractor: + * * A single C source file, so it should be easy to compile + * and run on any system with a C compiler. + * * Extremely portable standard C. The only non-ANSI function + * used is mkdir(). + * * Reads basic ustar tar archives. + * * Does not require libarchive or any other special library. + * + * To compile: cc -o untar untar.c + * + * Usage: untar <archive> + * + * In particular, this program should be sufficient to extract the + * distribution for libarchive, allowing people to bootstrap + * libarchive on systems that do not already have a tar program. + * + * To unpack libarchive-x.y.z.tar.gz: + * * gunzip libarchive-x.y.z.tar.gz + * * untar libarchive-x.y.z.tar + * + * Written by Tim Kientzle, March 2009. + * + * Released into the public domain. + */ + +/* These are all highly standard and portable headers. */ +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +/* This is for mkdir(); this may need to be changed for some platforms. */ +#include <sys/stat.h> /* For mkdir() */ + +/* Parse an octal number, ignoring leading and trailing nonsense. */ +static int +parseoct(const char *p, size_t n) +{ + int i = 0; + + while (*p < '0' || *p > '7') { + ++p; + --n; + } + while (*p >= '0' && *p <= '7' && n > 0) { + i *= 8; + i += *p - '0'; + ++p; + --n; + } + return (i); +} + +/* Returns true if this is 512 zero bytes. */ +static int +is_end_of_archive(const char *p) +{ + int n; + for (n = 511; n >= 0; --n) + if (p[n] != '\0') + return (0); + return (1); +} + +/* Create a directory, including parent directories as necessary. */ +static void +create_dir(char *pathname, int mode) +{ + char *p; + int r; + + /* Strip trailing '/' */ + if (pathname[strlen(pathname) - 1] == '/') + pathname[strlen(pathname) - 1] = '\0'; + + /* Try creating the directory. */ + r = mkdir(pathname, mode); + + if (r != 0) { + /* On failure, try creating parent directory. */ + p = strrchr(pathname, '/'); + if (p != NULL) { + *p = '\0'; + create_dir(pathname, 0755); + *p = '/'; + r = mkdir(pathname, mode); + } + } + if (r != 0) + fprintf(stderr, "Could not create directory %s\n", pathname); +} + +/* Create a file, including parent directory as necessary. */ +static FILE * +create_file(char *pathname, int mode) +{ + FILE *f; + f = fopen(pathname, "w+"); + if (f == NULL) { + /* Try creating parent dir and then creating file. */ + char *p = strrchr(pathname, '/'); + if (p != NULL) { + *p = '\0'; + create_dir(pathname, 0755); + *p = '/'; + f = fopen(pathname, "w+"); + } + } + return (f); +} + +/* Verify the tar checksum. */ +static int +verify_checksum(const char *p) +{ + int n, u = 0; + for (n = 0; n < 512; ++n) { + if (n < 148 || n > 155) + /* Standard tar checksum adds unsigned bytes. */ + u += ((unsigned char *)p)[n]; + else + u += 0x20; + + } + return (u == parseoct(p + 148, 8)); +} + +/* Extract a tar archive. */ +static void +untar(FILE *a, const char *path) +{ + char buff[512]; + FILE *f = NULL; + size_t bytes_read; + int filesize; + + printf("Extracting from %s\n", path); + for (;;) { + bytes_read = fread(buff, 1, 512, a); + if (bytes_read < 512) { + fprintf(stderr, + "Short read on %s: expected 512, got %d\n", + path, bytes_read); + return; + } + if (is_end_of_archive(buff)) { + printf("End of %s\n", path); + return; + } + if (!verify_checksum(buff)) { + fprintf(stderr, "Checksum failure\n"); + return; + } + filesize = parseoct(buff + 124, 12); + switch (buff[156]) { + case '1': + printf(" Ignoring hardlink %s\n", buff); + break; + case '2': + printf(" Ignoring symlink %s\n", buff); + break; + case '3': + printf(" Ignoring character device %s\n", buff); + break; + case '4': + printf(" Ignoring block device %s\n", buff); + break; + case '5': + printf(" Extracting dir %s\n", buff); + create_dir(buff, parseoct(buff + 100, 8)); + filesize = 0; + break; + case '6': + printf(" Ignoring FIFO %s\n", buff); + break; + default: + printf(" Extracting file %s\n", buff); + f = create_file(buff, parseoct(buff + 100, 8)); + break; + } + while (filesize > 0) { + bytes_read = fread(buff, 1, 512, a); + if (bytes_read < 512) { + fprintf(stderr, + "Short read on %s: Expected 512, got %d\n", + path, bytes_read); + return; + } + if (filesize < 512) + bytes_read = filesize; + if (f != NULL) { + if (fwrite(buff, 1, bytes_read, f) + != bytes_read) + { + fprintf(stderr, "Failed write\n"); + fclose(f); + f = NULL; + } + } + filesize -= bytes_read; + } + if (f != NULL) { + fclose(f); + f = NULL; + } + } +} + +int +main(int argc, char **argv) +{ + FILE *a; + + ++argv; /* Skip program name */ + for ( ;*argv != NULL; ++argv) { + a = fopen(*argv, "r"); + if (a == NULL) + fprintf(stderr, "Unable to open %s\n", *argv); + else { + untar(a, *argv); + fclose(a); + } + } + return (0); +} |