| /* |
| * This file is in the public domain. |
| * Use it as you wish. |
| */ |
| |
| /* |
| * This is a compact tar extraction program whose primary goal is |
| * small size. Statically linked, it can be under 64k, depending on |
| * how cleanly factored your system libraries are. Note that this |
| * uses the standard libarchive, without any special recompilation. |
| * The only functional concession is that this program uses the |
| * uid/gid from the archive instead of doing uname/gname lookups. |
| * (Call archive_write_disk_set_standard_lookup() to enable |
| * uname/gname lookups, but be aware that this can add 500k or more to |
| * a static executable, depending on the system libraries.) |
| * |
| * To build: |
| * gcc -static -Wall -o untar untar.c -larchive |
| * strip untar |
| * |
| * For fun, statically compile the following simple hello.c program |
| * and compare the size. (On my system, the result is 89k, untar is |
| * 69k.) |
| * |
| * #include <stdio.h> |
| * int main(int argc, char **argv) { |
| * printf("hello, world\n"); |
| * return(0); |
| * } |
| */ |
| |
| #include <sys/types.h> |
| __FBSDID("$FreeBSD$"); |
| |
| #include <sys/stat.h> |
| |
| #include <archive.h> |
| #include <archive_entry.h> |
| #include <fcntl.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <unistd.h> |
| |
| static void errmsg(const char *); |
| static void extract(const char *filename, int do_extract, int flags); |
| static int copy_data(struct archive *, struct archive *); |
| static void msg(const char *); |
| static void usage(void); |
| |
| static int verbose = 0; |
| |
| int |
| main(int argc, const char **argv) |
| { |
| const char *filename = NULL; |
| int compress, flags, mode, opt; |
| |
| (void)argc; |
| mode = 'x'; |
| verbose = 0; |
| compress = '\0'; |
| flags = ARCHIVE_EXTRACT_TIME; |
| |
| /* Among other sins, getopt(3) pulls in printf(3). */ |
| while (*++argv != NULL && **argv == '-') { |
| const char *p = *argv + 1; |
| |
| while ((opt = *p++) != '\0') { |
| switch (opt) { |
| case 'f': |
| if (*p != '\0') |
| filename = p; |
| else |
| filename = *++argv; |
| p += strlen(p); |
| break; |
| case 'p': |
| flags |= ARCHIVE_EXTRACT_PERM; |
| flags |= ARCHIVE_EXTRACT_ACL; |
| flags |= ARCHIVE_EXTRACT_FFLAGS; |
| break; |
| case 't': |
| mode = opt; |
| break; |
| case 'v': |
| verbose++; |
| break; |
| case 'x': |
| mode = opt; |
| break; |
| default: |
| usage(); |
| } |
| } |
| } |
| |
| switch (mode) { |
| case 't': |
| extract(filename, 0, flags); |
| break; |
| case 'x': |
| extract(filename, 1, flags); |
| break; |
| } |
| |
| return (0); |
| } |
| |
| |
| static void |
| extract(const char *filename, int do_extract, int flags) |
| { |
| struct archive *a; |
| struct archive *ext; |
| struct archive_entry *entry; |
| int r; |
| |
| a = archive_read_new(); |
| ext = archive_write_disk_new(); |
| archive_write_disk_set_options(ext, flags); |
| /* |
| * Note: archive_write_disk_set_standard_lookup() is useful |
| * here, but it requires library routines that can add 500k or |
| * more to a static executable. |
| */ |
| archive_read_support_format_tar(a); |
| /* |
| * On my system, enabling other archive formats adds 20k-30k |
| * each. Enabling gzip decompression adds about 20k. |
| * Enabling bzip2 is more expensive because the libbz2 library |
| * isn't very well factored. |
| */ |
| if (filename != NULL && strcmp(filename, "-") == 0) |
| filename = NULL; |
| if ((r = archive_read_open_file(a, filename, 10240))) { |
| errmsg(archive_error_string(a)); |
| errmsg("\n"); |
| exit(r); |
| } |
| for (;;) { |
| r = archive_read_next_header(a, &entry); |
| if (r == ARCHIVE_EOF) |
| break; |
| if (r != ARCHIVE_OK) { |
| errmsg(archive_error_string(a)); |
| errmsg("\n"); |
| exit(1); |
| } |
| if (verbose && do_extract) |
| msg("x "); |
| if (verbose || !do_extract) |
| msg(archive_entry_pathname(entry)); |
| if (do_extract) { |
| r = archive_write_header(ext, entry); |
| if (r != ARCHIVE_OK) |
| errmsg(archive_error_string(a)); |
| else |
| copy_data(a, ext); |
| } |
| if (verbose || !do_extract) |
| msg("\n"); |
| } |
| archive_read_close(a); |
| archive_read_finish(a); |
| exit(0); |
| } |
| |
| static int |
| copy_data(struct archive *ar, struct archive *aw) |
| { |
| int r; |
| const void *buff; |
| size_t size; |
| off_t offset; |
| |
| for (;;) { |
| r = archive_read_data_block(ar, &buff, &size, &offset); |
| if (r == ARCHIVE_EOF) { |
| errmsg(archive_error_string(ar)); |
| return (ARCHIVE_OK); |
| } |
| if (r != ARCHIVE_OK) |
| return (r); |
| r = archive_write_data_block(aw, buff, size, offset); |
| if (r != ARCHIVE_OK) { |
| errmsg(archive_error_string(ar)); |
| return (r); |
| } |
| } |
| } |
| |
| static void |
| msg(const char *m) |
| { |
| write(1, m, strlen(m)); |
| } |
| |
| static void |
| errmsg(const char *m) |
| { |
| write(2, m, strlen(m)); |
| } |
| |
| static void |
| usage(void) |
| { |
| const char *m = "Usage: untar [-tvx] [-f file] [file]\n"; |
| errmsg(m); |
| exit(1); |
| } |