losetup: support -f (Loic Grenie <loic.grenie@gmail.com>)

function                                             old     new   delta
losetup_main                                         238     278     +40
packed_usage                                       23021   23027      +6
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 46/0)               Total: 46 bytes

diff --git a/include/usage.h b/include/usage.h
index 09c8fa7d16238e5729dc21b73b2a022bce6d28fe..b028f5a5c2c0af843045757be48ab143e32850c3 100644 (file)
--- a/include/usage.h
+++ b/include/usage.h
@@ -1868,19 +1868,21 @@
        "       -f      Output data as the log grows"
 
 #define losetup_trivial_usage \
-       "[-o OFFSET] [-d] LOOPDEVICE [FILE]]"
+       "[-o OFS] LOOPDEV FILE - associate loop devices\n" \
+       "       losetup -d LOOPDEV - disassociate\n" \
+       "       losetup [-f] - show"
 #define losetup_full_usage \
-       "(Dis)associate LOOPDEVICE with FILE, or display current associations" \
-       "\n\nOptions:\n" \
-       "       -d              Disassociate LOOPDEVICE\n" \
-       "       -o OFFSET       Start OFFSET bytes into FILE"
+       "Options:\n" \
+       "       -o OFS  Start OFS bytes into FILE\n" \
+       "       -f      Show first free loop device"
 #define losetup_notes_usage \
        "No arguments will display all current associations.\n" \
        "One argument (losetup /dev/loop1) will display the current association\n" \
        "(if any), or disassociate it (with -d). The display shows the offset\n" \
        "and filename of the file the loop device is currently bound to.\n\n" \
        "Two arguments (losetup /dev/loop1 file.img) create a new association,\n" \
-       "with an optional offset (-o 12345). Encryption is not yet supported.\n\n"
+       "with an optional offset (-o 12345). Encryption is not yet supported.\n" \
+       "losetup -f will show the first loop free loop device\n\n"
 
 #define ls_trivial_usage \
        "[-1Aa" USE_FEATURE_LS_TIMESTAMPS("c") "Cd" \

diff --git a/util-linux/losetup.c b/util-linux/losetup.c
index 9409cdff559a35540aae19987316be6028936b8c..57e8569dc3c218829d196834c956a61be639120f 100644 (file)
--- a/util-linux/losetup.c
+++ b/util-linux/losetup.c
@@ -14,54 +14,68 @@
 int losetup_main(int argc, char **argv);
 int losetup_main(int argc, char **argv)
 {
+       char dev[] = LOOP_NAME"0";
        unsigned opt;
        char *opt_o;
+       char *s;
        unsigned long long offset = 0;
 
-       opt = getopt32(argv, "do:", &opt_o);
+       /* max 2 args, all opts are mutially exclusive */
+       opt_complementary = "?2:d--of:o--df:f-do";
+       opt = getopt32(argv, "do:f", &opt_o);
        argc -= optind;
        argv += optind;
 
-       if (opt == 0x3) // -d + -o (illegal)
+       if (opt == 0x2) // -o
+               offset = xatoull(opt_o);
+
+       if (opt == 0x4 && argc) // -f does not take any argument
                bb_show_usage();
 
        if (opt == 0x1) { // -d
                /* detach takes exactly one argument */
                if (argc != 1)
                        bb_show_usage();
-               if (!del_loop(argv[0]))
-                       return EXIT_SUCCESS;
-               bb_perror_nomsg_and_die();
+               if (del_loop(argv[0]))
+                       bb_perror_nomsg_and_die();
+               return EXIT_SUCCESS;
        }
 
-       if (opt == 0x2) // -o
-               offset = xatoull(opt_o);
-
-       /* -o or no option */
-
        if (argc == 2) {
+               /* -o or no option */
                if (set_loop(&argv[0], argv[1], offset) < 0)
                        bb_perror_nomsg_and_die();
-       } else if (argc == 1) {
-               char *s = query_loop(argv[0]);
+               return EXIT_SUCCESS;
+       }
+
+       if (argc == 1) {
+               /* -o or no option */
+               s = query_loop(argv[0]);
                if (!s)
                        bb_perror_nomsg_and_die();
                printf("%s: %s\n", argv[0], s);
                if (ENABLE_FEATURE_CLEAN_UP)
                        free(s);
-       } else {
-               char dev[sizeof(LOOP_NAME"0")] = LOOP_NAME"0";
-               char c;
-               for (c = '0'; c <= '9'; ++c) {
-                       char *s;
-                       dev[sizeof(LOOP_NAME"0")-2] = c;
-                       s = query_loop(dev);
-                       if (s) {
-                               printf("%s: %s\n", dev, s);
-                               if (ENABLE_FEATURE_CLEAN_UP)
-                                       free(s);
+               return EXIT_SUCCESS;
+       }
+
+       /* -o, -f or no option */
+       while (1) {
+               s = query_loop(dev);
+               if (!s) {
+                       if (opt == 0x4) {
+                               printf("%s\n", dev);
+                               return EXIT_SUCCESS;
                        }
+               } else {
+                       if (opt != 0x4)
+                               printf("%s: %s\n", dev, s);
+                       if (ENABLE_FEATURE_CLEAN_UP)
+                               free(s);
                }
+
+               if (++dev[sizeof(dev) - 2] > '9')
+                       break;
        }
        return EXIT_SUCCESS;
 }