Move the "--size @FILE" file size reading into its own function for clarity; standardise its error message format to "program: file: message: detail"; uniquely name variables; refuse to accept a directory as a file; and with this option, try reading the size of a block device from sysfs if we can, to avoid requiring read permissions on the device.
This commit is contained in:
Andrew Wood
@@ -169,6 +169,9 @@
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/* Define to 1 if you have the <sys/stat.h> header file. */
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#undef HAVE_SYS_STAT_H
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/* Define to 1 if you have the <sys/sysmacros.h> header file. */
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#undef HAVE_SYS_SYSMACROS_H
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/* Define to 1 if you have the <sys/time.h> header file. */
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#undef HAVE_SYS_TIME_H
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+162
-41
@@ -15,6 +15,14 @@
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#include <string.h>
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#include <errno.h>
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#include <sys/stat.h>
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#ifdef HAVE_SYS_SYSMACROS_H
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#include <sys/sysmacros.h>
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#ifdef major
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#ifdef minor
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#define CAN_BUILD_SYSFS_FILENAME 1
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#endif
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#endif
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#endif
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#include <fcntl.h>
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#include <unistd.h>
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#ifdef HAVE_GETOPT_H
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@@ -89,6 +97,154 @@ bool opts_add_file(opts_t opts, const char *filename)
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}
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/*
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* Set opts->size from the size of the file whose name is size_file,
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* returning false (and reporting the error) if there is a problem.
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*
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* If size_file points to a block device, the size of the block device is
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* used.
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*/
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static bool opts_use_size_of_file(opts_t opts, const char *size_file)
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{
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struct stat sb;
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int stat_rc;
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#ifdef CAN_BUILD_SYSFS_FILENAME
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char sysfs_filename[512]; /* flawfinder: ignore */
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FILE *sysfs_fptr;
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long long sysfs_size;
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#endif /* CAN_BUILD_SYSFS_FILENAME */
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int device_fd;
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off_t device_size;
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/*
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* flawfinder rationale: sysfs_filename is only used with
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* pv_snprintf() which guarantees it will be bounded and zero
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* terminated.
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*/
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stat_rc = 0;
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memset(&sb, 0, sizeof(sb));
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stat_rc = stat(size_file, &sb);
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if (0 != stat_rc) {
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/*@-mustfreefresh@ */
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/*
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* splint note: the gettext calls made by _() cause memory
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* leak warnings, but in this case it's unavoidable, and
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* mitigated by the fact we only translate each string once.
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*/
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fprintf(stderr, "%s: %s: %s: %s\n",
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opts->program_name, size_file, _("failed to stat file"), strerror(errno));
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return false;
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/*@+mustfreefresh@ */
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}
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/* This was a regular file - use its size and return. */
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if (S_ISREG((mode_t) (sb.st_mode))) {
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opts->size = (off_t) (sb.st_size);
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return true;
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}
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/* This was a directory - report an error. */
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if (S_ISDIR((mode_t) (sb.st_mode))) {
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/*@-mustfreefresh@ *//* see above */
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fprintf(stderr, "%s: %s: %s\n", opts->program_name, size_file, _("is a directory"));
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return false;
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/*@+mustfreefresh@ */
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}
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/* This was not a block device - just use the size and return. */
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if (!S_ISBLK((mode_t) (sb.st_mode))) {
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opts->size = (off_t) (sb.st_size);
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return true;
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}
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/*
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* Block device - determine its size by looking for
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* /sys/dev/block/MAJOR:MINOR/size, and if that fails, try opening
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* the file and seeking to the end.
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*/
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#ifdef CAN_BUILD_SYSFS_FILENAME
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/*
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* Try the sysfs method - lightest touch and requires no read access
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* to the actual block device.
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*/
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memset(sysfs_filename, 0, sizeof(sysfs_filename));
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if (pv_snprintf
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(sysfs_filename, sizeof(sysfs_filename), "/sys/dev/block/%u:%u/size", major(sb.st_rdev),
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minor(sb.st_rdev)) < 0) {
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/*@-mustfreefresh@ *//* see above */
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fprintf(stderr, "%s: %s: %s: %s\n",
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opts->program_name, size_file, _("failed to generate sysfs filename"), strerror(errno));
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return false;
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/*@+mustfreefresh@ */
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}
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sysfs_fptr = fopen(sysfs_filename, "r"); /* flawfinder: ignore */
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/*
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* flawfinder rationale: sysfs is trusted here, the filename is
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* predictable, and we are restricted to reading one number.
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*/
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if (NULL != sysfs_fptr) {
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sysfs_size = -1;
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if (1 == fscanf(sysfs_fptr, "%lld", &sysfs_size)) {
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/* Read successful - use the value (* 512) and return. */
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(void) fclose(sysfs_fptr);
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opts->size = (off_t) sysfs_size *512;
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return true;
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}
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/* Read not successful - report the error and return. */
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/* NB we must fclose() after reporting to retain errno. */
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/*@-mustfreefresh@ *//* see above */
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fprintf(stderr, "%s: %s: %s: %s\n",
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opts->program_name, size_file, _("failed to read sysfs size file"), strerror(errno));
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(void) fclose(sysfs_fptr);
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return false;
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/*@+mustfreefresh@ */
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}
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#endif /* CAN_BUILD_SYSFS_FILENAME */
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/*
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* Try opening the block device and seeking to the end.
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*/
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device_fd = open(size_file, O_RDONLY); /* flawfinder: ignore */
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/*
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* flawfinder rationale: the filename is under the direct control of
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* the operator by its nature, so we can't refuse to open symlinks
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* etc as that would be counterintuitive.
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*/
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if (device_fd < 0) {
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/*@-mustfreefresh@ *//* see above */
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fprintf(stderr, "%s: %s: %s: %s\n",
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opts->program_name, size_file, _("failed to open block device"), strerror(errno));
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return false;
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/*@+mustfreefresh@ */
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}
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device_size = (off_t) lseek(device_fd, 0, SEEK_END);
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if (device_size < 0) {
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/*@-mustfreefresh@ *//* see above */
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fprintf(stderr, "%s: %s: %s: %s\n",
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opts->program_name, size_file, _("failed to determine size of block device"), strerror(errno));
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/* NB close() after reporting error, to preserve errno. */
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(void) close(device_fd);
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return false;
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/*@+mustfreefresh@ */
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}
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(void) close(device_fd);
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/* Use the size we found. */
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opts->size = device_size;
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return true;
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}
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/*
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* Parse the given command-line arguments into an opts_t object, handling
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* "help" and "version" options internally.
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@@ -374,51 +530,16 @@ opts_t opts_parse(unsigned int argc, char **argv)
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opts->delay_start = pv_getnum_interval(optarg);
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break;
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case 's':
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/* Permit "@<filename>" as well as just a number. */
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if ('@' == *optarg) {
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if ('@' != *optarg) {
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/* A number was passed, not "@<filename>". */
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opts->size = pv_getnum_size(optarg, opts->decimal_units);
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} else {
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/* Permit "@<filename>". */
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const char *size_file = 1 + optarg;
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struct stat sb;
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int rc;
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rc = 0;
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memset(&sb, 0, sizeof(sb));
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rc = stat(size_file, &sb);
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if (0 != rc) {
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/*@-mustfreefresh@ *//* see above */
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fprintf(stderr, "%s: %s %s: %s\n",
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opts->program_name,
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_("failed to stat file"), size_file, strerror(errno));
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if (!opts_use_size_of_file(opts, size_file)) {
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opts_free(opts);
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return NULL;
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/*@+mustfreefresh@ */
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}
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opts->size = (off_t) (sb.st_size);
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if (0 == opts->size && S_ISBLK(sb.st_mode)) {
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int fd = open(size_file, O_RDONLY);
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if (fd < 0) {
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/*@-mustfreefresh@ *//* see above */
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fprintf(stderr, "%s: %s %s: %s\n",
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opts->program_name,
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_("failed to open block device"), size_file, strerror(errno));
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opts_free(opts);
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return NULL;
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/*@+mustfreefresh@ */
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}
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off_t size = lseek(fd, 0, SEEK_END);
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close(fd);
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if (size < 0) {
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/*@-mustfreefresh@ *//* see above */
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fprintf(stderr, "%s: %s %s: %s\n",
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opts->program_name,
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_("failed to seek size of block device"), size_file, strerror(errno));
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opts_free(opts);
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return NULL;
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/*@+mustfreefresh@ */
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}
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opts->size = size;
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}
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} else {
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opts->size = pv_getnum_size(optarg, opts->decimal_units);
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}
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break;
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case 'l':
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