modprobe-small: add depfile creation

1 files changed, 108 insertions, 7 deletions

diff --git a/modutils/modprobe-small.c b/modutils/modprobe-small.c
index 1a9d98422..cf9be47a6 100644
--- a/modutils/modprobe-small.c
+++ b/modutils/modprobe-small.c
@@ -43,6 +43,7 @@ typedef struct module_info {
 struct globals {
         module_info *modinfo;
         char *module_load_options;
+        smallint dep_bb_seen;
         int module_count;
         int module_found_idx;
         int stringbuf_idx;
@@ -51,6 +52,7 @@ struct globals {
 };
 #define G (*ptr_to_globals)
 #define modinfo             (G.modinfo            )
+#define dep_bb_seen         (G.dep_bb_seen        )
 #define module_count        (G.module_count       )
 #define module_found_idx    (G.module_found_idx   )
 #define module_load_options (G.module_load_options)
@@ -320,13 +322,28 @@ static FAST_FUNC int fileAction(const char *pathname,
         return TRUE;
 }
 
-static void load_dep_bb(void)
+static int load_dep_bb(void)
 {
         char *line;
         FILE *fp = fopen(DEPFILE_BB, "r");
 
         if (!fp)
-                return;
+                return 0;
+
+        dep_bb_seen = 1;
+        dbg1_error_msg("loading "DEPFILE_BB);
+
+        /* Why? There is a rare scenario: we did not find modprobe.dep.bb,
+         * we scanned the dir and found no module by name, then we search
+         * for alias (full scan), and we decided to generate modprobe.dep.bb.
+         * But we see modprobe.dep.bb.new! Other modprobe is at work!
+         * We wait and other modprobe renames it to modprobe.dep.bb.
+         * Now we can use it.
+         * But we already have modinfo[] filled, and "module_count = 0"
+         * makes us start anew. Yes, we leak modinfo[].xxx pointers -
+         * there is not much of data there anyway. */
+        module_count = 0;
+        memset(&modinfo[0], 0, sizeof(modinfo[0]));
 
         while ((line = xmalloc_fgetline(fp)) != NULL) {
                 char* space;
@@ -355,13 +372,74 @@ static void load_dep_bb(void)
                         free(line);
                 }
         }
+        return 1;
+}
+
+static int start_dep_bb_writeout(void)
+{
+        int fd;
+
+        fd = open(DEPFILE_BB".new", O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, 0644);
+        if (fd < 0) {
+                if (errno == EEXIST) {
+                        int count = 5 * 20;
+                        dbg1_error_msg(DEPFILE_BB".new exists, waiting for "DEPFILE_BB);
+                        while (1) {
+                                usleep(1000*1000 / 20);
+                                if (load_dep_bb()) {
+                                        dbg1_error_msg(DEPFILE_BB" appeared");
+                                        return -2; /* magic number */
+                                }
+                                if (!--count)
+                                        break;
+                        }
+                        bb_error_msg("deleting stale %s", DEPFILE_BB".new");
+                        fd = open_or_warn(DEPFILE_BB".new", O_WRONLY | O_CREAT | O_TRUNC);
+                }
+        }
+        dbg1_error_msg("opened "DEPFILE_BB".new:%d", fd);
+        return fd;
+}
+
+static void write_out_dep_bb(int fd)
+{
+        int i;
+        FILE *fp;
+
+        /* We want good error reporting. fdprintf is not good enough. */
+        fp = fdopen(fd, "w");
+        if (!fp) {
+                close(fd);
+                goto err;
+        }
+        i = 0;
+        while (modinfo[i].pathname) {
+                fprintf(fp, "%s%s%s\n" "%s%s\n",
+                        modinfo[i].pathname, modinfo[i].aliases[0] ? " " : "", modinfo[i].aliases,
+                        modinfo[i].deps, modinfo[i].deps[0] ? "\n" : "");
+                i++;
+        }
+        /* Badly formatted depfile is a no-no. Be paranoid. */
+        errno = 0;
+        if (ferror(fp) | fclose(fp))
+                goto err;
+        if (rename(DEPFILE_BB".new", DEPFILE_BB) != 0) {
+ err:
+                bb_perror_msg("can't create %s", DEPFILE_BB);
+                unlink(DEPFILE_BB".new");
+        } else {
+                dbg1_error_msg("created "DEPFILE_BB);
+        }
 }
 
 static module_info* find_alias(const char *alias)
 {
         int i;
+        int dep_bb_fd;
+        module_info *result;
         dbg1_error_msg("find_alias('%s')", alias);
 
+ try_again:
         /* First try to find by name (cheaper) */
         i = 0;
         while (modinfo[i].pathname) {
@@ -376,13 +454,22 @@ static module_info* find_alias(const char *alias)
                 i++;
         }
 
+        /* Ok, we definitely have to scan module bodies. This is a good
+         * moment to generate modprobe.dep.bb, if it does not exist yet */
+        dep_bb_fd = dep_bb_seen ? -1 : start_dep_bb_writeout();
+        if (dep_bb_fd == -2) /* modprobe.dep.bb appeared? */
+                goto try_again;
+
         /* Scan all module bodies, extract modinfo (it contains aliases) */
         i = 0;
+        result = NULL;
         while (modinfo[i].pathname) {
                 char *desc, *s;
                 if (!modinfo[i].aliases) {
                         parse_module(&modinfo[i], modinfo[i].pathname);
                 }
+                if (result)
+                        continue;
                 /* "alias1 symbol:sym1 alias2 symbol:sym2" */
                 desc = str_2_list(modinfo[i].aliases);
                 /* Does matching substring exist? */
@@ -392,17 +479,25 @@ static module_info* find_alias(const char *alias)
                          * "pci:v000010DEd000000D9sv*sd*bc*sc*i*".
                          * Plain strcmp() won't catch that */
                         if (fnmatch(s, alias, 0) == 0) {
-                                free(desc);
                                 dbg1_error_msg("found alias '%s' in module '%s'",
                                                 alias, modinfo[i].pathname);
-                                return &modinfo[i];
+                                result = &modinfo[i];
+                                break;
                         }
                 }
                 free(desc);
+                if (result && dep_bb_fd < 0)
+                        return result;
                 i++;
         }
-        dbg1_error_msg("find_alias '%s' returns NULL", alias);
-        return NULL;
+
+        /* Create module.dep.bb if needed */
+        if (dep_bb_fd >= 0) {
+                write_out_dep_bb(dep_bb_fd);
+        }
+
+        dbg1_error_msg("find_alias '%s' returns %p", alias, result);
+        return result;
 }
 
 #if ENABLE_FEATURE_MODPROBE_SMALL_CHECK_ALREADY_LOADED
@@ -497,7 +592,7 @@ static void process_module(char *name, const char *cmdline_options)
 
         /* rmmod? unload it by name */
         if (is_rmmod) {
-                if (delete_module(name, O_NONBLOCK|O_EXCL) != 0
+                if (delete_module(name, O_NONBLOCK | O_EXCL) != 0
                  && !(option_mask32 & OPT_q)
                 ) {
                         bb_perror_msg("remove '%s'", name);
@@ -511,6 +606,8 @@ static void process_module(char *name, const char *cmdline_options)
         }
 
         if (!info) { /* both dirscan and find_alias found nothing */
+                bb_error_msg("module '%s' not found", name);
+//TODO: _and_die()?
                 goto ret;
         }
 
@@ -637,6 +734,10 @@ int modprobe_main(int argc UNUSED_PARAM, char **argv)
                 argv[1] = NULL;
 #endif
 
+        /* Prevent ugly corner cases with no modules at all */
+        modinfo = xzalloc(sizeof(modinfo[0]));
+
+        /* Try to load modprobe.dep.bb */
         load_dep_bb();
 
         /* Load/remove modules.