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Diffstat (limited to '')
| -rw-r--r-- | libfdisk/src/utils.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/libfdisk/src/utils.c b/libfdisk/src/utils.c new file mode 100644 index 0000000..1154090 --- /dev/null +++ b/libfdisk/src/utils.c @@ -0,0 +1,213 @@ + +#include "fdiskP.h" +#include "pathnames.h" +#include "canonicalize.h" + +#include <ctype.h> + +/** + * SECTION: utils + * @title: Utils + * @short_description: misc fdisk functions + */ + +static int read_from_device(struct fdisk_context *cxt, + unsigned char *buf, + uintmax_t start, size_t size) +{ + ssize_t r; + + assert(cxt); + + DBG(CXT, ul_debugobj(cxt, "reading: offset=%ju, size=%zu", + start, size)); + + r = lseek(cxt->dev_fd, start, SEEK_SET); + if (r == -1) + { + DBG(CXT, ul_debugobj(cxt, "failed to seek to offset %ju: %m", start)); + return -errno; + } + + r = read(cxt->dev_fd, buf, size); + if (r < 0 || (size_t)r != size) { + if (!errno) + errno = EINVAL; /* probably too small file/device */ + DBG(CXT, ul_debugobj(cxt, "failed to read %zu from offset %ju: %m", + size, start)); + return -errno; + } + + return 0; +} + + +/* + * Zeros in-memory first sector buffer + */ +int fdisk_init_firstsector_buffer(struct fdisk_context *cxt, + unsigned int protect_off, + unsigned int protect_size) +{ + if (!cxt) + return -EINVAL; + + assert(protect_off + protect_size <= cxt->sector_size); + + if (!cxt->firstsector || cxt->firstsector_bufsz != cxt->sector_size) { + /* Let's allocate a new buffer if no allocated yet, or the + * current buffer has incorrect size */ + if (!cxt->parent || cxt->parent->firstsector != cxt->firstsector) + free(cxt->firstsector); + + DBG(CXT, ul_debugobj(cxt, "initialize in-memory first sector " + "buffer [sector_size=%lu]", cxt->sector_size)); + cxt->firstsector = calloc(1, cxt->sector_size); + if (!cxt->firstsector) + return -ENOMEM; + + cxt->firstsector_bufsz = cxt->sector_size; + return 0; + } + + DBG(CXT, ul_debugobj(cxt, "zeroize in-memory first sector buffer")); + memset(cxt->firstsector, 0, cxt->firstsector_bufsz); + + if (protect_size) { + /* + * It would be possible to reuse data from cxt->firstsector + * (call memset() for non-protected area only) and avoid one + * read() from the device, but it seems like a too fragile + * solution as we have no clue about stuff in the buffer -- + * maybe it was already modified. Let's re-read from the device + * to be sure. -- kzak 13-Apr-2015 + */ + DBG(CXT, ul_debugobj(cxt, "first sector protection enabled -- re-reading")); + read_from_device(cxt, cxt->firstsector, protect_off, protect_size); + } + return 0; +} + +int fdisk_read_firstsector(struct fdisk_context *cxt) +{ + int rc; + + assert(cxt); + assert(cxt->sector_size); + + rc = fdisk_init_firstsector_buffer(cxt, 0, 0); + if (rc) + return rc; + + assert(cxt->sector_size == cxt->firstsector_bufsz); + + + return read_from_device(cxt, cxt->firstsector, 0, cxt->sector_size); +} + +/** + * fdisk_partname: + * @dev: device name + * @partno: partition name + * + * Return: allocated buffer with partition name, use free() to deallocate. + */ +char *fdisk_partname(const char *dev, size_t partno) +{ + char *res = NULL; + const char *p = ""; + char *dev_mapped = NULL; + int w = 0; + + if (!dev || !*dev) { + if (asprintf(&res, "%zd", partno) > 0) + return res; + return NULL; + } + + /* It is impossible to predict /dev/dm-N partition names. */ + if (strncmp(dev, "/dev/dm-", sizeof("/dev/dm-") - 1) == 0) { + dev_mapped = canonicalize_dm_name (dev + 5); + if (dev_mapped) + dev = dev_mapped; + } + + w = strlen(dev); + if (isdigit(dev[w - 1])) +#ifdef __GNU__ + p = "s"; +#else + p = "p"; +#endif + + /* devfs kludge - note: fdisk partition names are not supposed + to equal kernel names, so there is no reason to do this */ + if (strcmp(dev + w - 4, "disc") == 0) { + w -= 4; + p = "part"; + } + + /* udev names partitions by appending -partN + e.g. ata-SAMSUNG_SV8004H_0357J1FT712448-part1 + multipath-tools kpartx.rules also append -partN */ + if ((strncmp(dev, _PATH_DEV_BYID, sizeof(_PATH_DEV_BYID) - 1) == 0) || + strncmp(dev, _PATH_DEV_BYPATH, sizeof(_PATH_DEV_BYPATH) - 1) == 0 || + strncmp(dev, "/dev/mapper", sizeof("/dev/mapper") - 1) == 0) { + + /* check for <name><partno>, e.g. mpatha1 */ + if (asprintf(&res, "%.*s%zu", w, dev, partno) <= 0) + res = NULL; + if (res && access(res, F_OK) == 0) + goto done; + + free(res); + + /* check for partition seperator "p" */ + if (asprintf(&res, "%.*sp%zu", w, dev, partno) <= 0) + res = NULL; + if (res && access(res, F_OK) == 0) + goto done; + + free(res); + + /* otherwise, default to "-path" */ + p = "-part"; + } + + if (asprintf(&res, "%.*s%s%zu", w, dev, p, partno) <= 0) + res = NULL; +done: + free(dev_mapped); + return res; +} + +#ifdef TEST_PROGRAM +struct fdisk_label *fdisk_new_dos_label(struct fdisk_context *cxt) { return NULL; } +struct fdisk_label *fdisk_new_bsd_label(struct fdisk_context *cxt) { return NULL; } + +static int test_partnames(struct fdisk_test *ts, int argc, char *argv[]) +{ + size_t i; + const char *disk = argv[1]; + + for (i = 0; i < 5; i++) { + char *p = fdisk_partname(disk, i + 1); + if (p) + printf("%zu: '%s'\n", i + 1, p); + free(p); + } + + return 0; +} + +int main(int argc, char *argv[]) +{ + struct fdisk_test tss[] = { + { "--partnames", test_partnames, "<diskname>" }, + { NULL } + }; + + return fdisk_run_test(tss, argc, argv); +} + +#endif |