fuser: code shrink, fixing default signal, exitcode and PID display

Defult signal is KILL, not TERM.
We used to not display PIDs with -k but without -s, but
upstream (fuser from PSmisc 22.7) still shows PIDs.
Filtering out of our own PID was buggy.

function                                             old     new   delta
fuser_main                                           669     918    +249
search_dev_inode                                      67      74      +7
add_pid                                               38      39      +1
scan_pid_maps                                        225     222      -3
add_inode                                             91      88      -3
packed_usage                                       27047   27039      -8
scan_dir_links                                       102      76     -26
scan_link                                             78      46     -32
file_to_dev_inode                                     64       -     -64
scan_proc_net                                        307       -    -307
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 3/5 up/down: 257/-443)         Total: -186 bytes

Signed-off-by: Maksym Kryzhanovskyy <xmaks@email.cz>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 125 insertions, 139 deletions

diff --git a/include/usage.h b/include/usage.h
index a295ab865..8f695f8b8 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -1474,9 +1474,9 @@
      "\n        -m      Find processes which use same fs as FILEs" \
      "\n        -4      Search only IPv4 space" \
      "\n        -6      Search only IPv6 space" \
-     "\n        -s      Silent: just exit with 0 if any processes are found" \
-     "\n        -k      Kill found processes (otherwise display PIDs)" \
-     "\n        -SIGNAL Signal to send (default: TERM)" \
+     "\n        -s      Don't display PIDs" \
+     "\n        -k      Kill found processes" \
+     "\n        -SIGNAL Signal to send (default: KILL)" \
 
 #define getenforce_trivial_usage NOUSAGE_STR
 #define getenforce_full_usage ""
diff --git a/procps/fuser.c b/procps/fuser.c
index dc3d01bda..7465d4554 100644
--- a/procps/fuser.c
+++ b/procps/fuser.c
@@ -31,6 +31,15 @@ typedef struct pid_list {
         pid_t pid;
 } pid_list;
 
+
+struct globals {
+        pid_list *pid_list_head;
+        inode_list *inode_list_head;
+};
+#define G (*(struct globals*)&bb_common_bufsiz1)
+#define INIT_G() do { } while (0)
+
+
 static dev_t find_socket_dev(void)
 {
         int fd = socket(AF_INET, SOCK_DGRAM, 0);
@@ -44,16 +53,6 @@ static dev_t find_socket_dev(void)
         return 0;
 }
 
-static int file_to_dev_inode(const char *filename, dev_t *dev, ino_t *inode)
-{
-        struct stat f_stat;
-        if (stat(filename, &f_stat))
-                return 0;
-        *inode = f_stat.st_ino;
-        *dev = f_stat.st_dev;
-        return 1;
-}
-
 static char *parse_net_arg(const char *arg, unsigned *port)
 {
         char path[20], tproto[5];
@@ -63,54 +62,54 @@ static char *parse_net_arg(const char *arg, unsigned *port)
         sprintf(path, "/proc/net/%s", tproto);
         if (access(path, R_OK) != 0)
                 return NULL;
-        return xstrdup(tproto);
+        return xstrdup(path);
 }
 
-static pid_list *add_pid(pid_list *plist, pid_t pid)
+static void add_pid(const pid_t pid)
 {
-        pid_list *curr = plist;
-        while (curr != NULL) {
-                if (curr->pid == pid)
-                        return plist;
-                curr = curr->next;
+        pid_list **curr = &G.pid_list_head;
+
+        while (*curr) {
+                if ((*curr)->pid == pid)
+                        return;
+                curr = &(*curr)->next;
         }
-        curr = xmalloc(sizeof(pid_list));
-        curr->pid = pid;
-        curr->next = plist;
-        return curr;
+
+        *curr = xzalloc(sizeof(pid_list));
+        (*curr)->pid = pid;
 }
 
-static inode_list *add_inode(inode_list *ilist, dev_t dev, ino_t inode)
+static void add_inode(const struct stat *st)
 {
-        inode_list *curr = ilist;
-        while (curr != NULL) {
-                if (curr->inode == inode && curr->dev == dev)
-                        return ilist;
-                curr = curr->next;
+        inode_list **curr = &G.inode_list_head;
+
+        while (*curr) {
+                if ((*curr)->dev == st->st_dev
+                 && (*curr)->inode == st->st_ino
+                ) {
+                        return;
+                }
+                curr = &(*curr)->next;
         }
-        curr = xmalloc(sizeof(inode_list));
-        curr->dev = dev;
-        curr->inode = inode;
-        curr->next = ilist;
-        return curr;
+
+        *curr = xzalloc(sizeof(inode_list));
+        (*curr)->dev = st->st_dev;
+        (*curr)->inode = st->st_ino;
 }
 
-static inode_list *scan_proc_net(const char *proto,
-                                unsigned port, inode_list *ilist)
+static void scan_proc_net(const char *path, unsigned port)
 {
-        char path[20], line[MAX_LINE + 1];
-        ino_t tmp_inode;
-        dev_t tmp_dev;
+        char line[MAX_LINE + 1];
         long long uint64_inode;
         unsigned tmp_port;
         FILE *f;
+        struct stat st;
 
-        tmp_dev = find_socket_dev();
+        st.st_dev = find_socket_dev();
 
-        sprintf(path, "/proc/net/%s", proto);
         f = fopen_for_read(path);
         if (!f)
-                return ilist;
+                return;
 
         while (fgets(line, MAX_LINE, f)) {
                 char addr[68];
@@ -124,22 +123,23 @@ static inode_list *scan_proc_net(const char *proto,
                         if (len > 8 && (option_mask32 & OPT_IP4))
                                 continue;
                         if (tmp_port == port) {
-                                tmp_inode = uint64_inode;
-                                ilist = add_inode(ilist, tmp_dev, tmp_inode);
+                                st.st_ino = uint64_inode;
+                                add_inode(&st);
                         }
                 }
         }
         fclose(f);
-        return ilist;
 }
 
-static int search_dev_inode(inode_list *ilist, dev_t dev, ino_t inode)
+static int search_dev_inode(const struct stat *st)
 {
+        inode_list *ilist = G.inode_list_head;
+
         while (ilist) {
-                if (ilist->dev == dev) {
+                if (ilist->dev == st->st_dev) {
                         if (option_mask32 & OPT_MOUNT)
                                 return 1;
-                        if (ilist->inode == inode)
+                        if (ilist->inode == st->st_ino)
                                 return 1;
                 }
                 ilist = ilist->next;
@@ -147,48 +147,42 @@ static int search_dev_inode(inode_list *ilist, dev_t dev, ino_t inode)
         return 0;
 }
 
-static pid_list *scan_pid_maps(const char *fname, pid_t pid,
-                                inode_list *ilist, pid_list *plist)
+static void scan_pid_maps(const char *fname, pid_t pid)
 {
         FILE *file;
         char line[MAX_LINE + 1];
         int major, minor;
-        ino_t inode;
         long long uint64_inode;
-        dev_t dev;
+        struct stat st;
 
         file = fopen_for_read(fname);
         if (!file)
-                return plist;
+                return;
+
         while (fgets(line, MAX_LINE, file)) {
                 if (sscanf(line, "%*s %*s %*s %x:%x %llu", &major, &minor, &uint64_inode) != 3)
                         continue;
-                inode = uint64_inode;
-                if (major == 0 && minor == 0 && inode == 0)
+                st.st_ino = uint64_inode;
+                if (major == 0 && minor == 0 && st.st_ino == 0)
                         continue;
-                dev = makedev(major, minor);
-                if (search_dev_inode(ilist, dev, inode))
-                        plist = add_pid(plist, pid);
+                st.st_dev = makedev(major, minor);
+                if (search_dev_inode(&st))
+                        add_pid(pid);
         }
         fclose(file);
-        return plist;
 }
 
-static pid_list *scan_link(const char *lname, pid_t pid,
-                                inode_list *ilist, pid_list *plist)
+static void scan_link(const char *lname, pid_t pid)
 {
-        ino_t inode;
-        dev_t dev;
+        struct stat st;
 
-        if (!file_to_dev_inode(lname, &dev, &inode))
-                return plist;
-        if (search_dev_inode(ilist, dev, inode))
-                plist = add_pid(plist, pid);
-        return plist;
+        if (stat(lname, &st) >= 0) {
+                if (search_dev_inode(&st))
+                        add_pid(pid);
+        }
 }
 
-static pid_list *scan_dir_links(const char *dname, pid_t pid,
-                                inode_list *ilist, pid_list *plist)
+static void scan_dir_links(const char *dname, pid_t pid)
 {
         DIR *d;
         struct dirent *de;
@@ -196,102 +190,73 @@ static pid_list *scan_dir_links(const char *dname, pid_t pid,
 
         d = opendir(dname);
         if (!d)
-                return plist;
+                return;
+
         while ((de = readdir(d)) != NULL) {
                 lname = concat_subpath_file(dname, de->d_name);
                 if (lname == NULL)
                         continue;
-                plist = scan_link(lname, pid, ilist, plist);
+                scan_link(lname, pid);
                 free(lname);
         }
         closedir(d);
-        return plist;
 }
 
 /* NB: does chdir internally */
-static pid_list *scan_proc_pids(inode_list *ilist)
+static void scan_proc_pids(void)
 {
         DIR *d;
         struct dirent *de;
         pid_t pid;
-        pid_list *plist;
 
         xchdir("/proc");
         d = opendir("/proc");
         if (!d)
-                return NULL;
+                return;
 
-        plist = NULL;
         while ((de = readdir(d)) != NULL) {
                 pid = (pid_t)bb_strtou(de->d_name, NULL, 10);
                 if (errno)
                         continue;
                 if (chdir(de->d_name) < 0)
                         continue;
-                plist = scan_link("cwd", pid, ilist, plist);
-                plist = scan_link("exe", pid, ilist, plist);
-                plist = scan_link("root", pid, ilist, plist);
-                plist = scan_dir_links("fd", pid, ilist, plist);
-                plist = scan_dir_links("lib", pid, ilist, plist);
-                plist = scan_dir_links("mmap", pid, ilist, plist);
-                plist = scan_pid_maps("maps", pid, ilist, plist);
-                xchdir("/proc");
-        }
-        closedir(d);
-        return plist;
-}
+                scan_link("cwd", pid);
+                scan_link("exe", pid);
+                scan_link("root", pid);
 
-static int print_pid_list(pid_list *plist)
-{
-        while (plist != NULL) {
-                printf("%u ", (unsigned)plist->pid);
-                plist = plist->next;
-        }
-        bb_putchar('\n');
-        return 1;
-}
-
-static int kill_pid_list(pid_list *plist, int sig)
-{
-        pid_t mypid = getpid();
-        int success = 1;
+                scan_dir_links("fd", pid);
+                scan_dir_links("lib", pid);
+                scan_dir_links("mmap", pid);
 
-        while (plist != NULL) {
-                if (plist->pid != mypid) {
-                        if (kill(plist->pid, sig) != 0) {
-                                bb_perror_msg("kill pid %u", (unsigned)plist->pid);
-                                success = 0;
-                        }
-                }
-                plist = plist->next;
+                scan_pid_maps("maps", pid);
+                xchdir("/proc");
         }
-        return success;
+        closedir(d);
 }
 
 int fuser_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int fuser_main(int argc UNUSED_PARAM, char **argv)
 {
         pid_list *plist;
-        inode_list *ilist;
+        pid_t mypid;
         char **pp;
-        dev_t dev;
-        ino_t inode;
+        struct stat st;
         unsigned port;
         int opt;
-        int success;
+        int exitcode;
         int killsig;
 /*
-fuser [options] FILEs or PORT/PROTOs
+fuser [OPTIONS] FILE or PORT/PROTO
 Find processes which use FILEs or PORTs
         -m      Find processes which use same fs as FILEs
         -4      Search only IPv4 space
         -6      Search only IPv6 space
-        -s      Silent: just exit with 0 if any processes are found
-        -k      Kill found processes (otherwise display PIDs)
-        -SIGNAL Signal to send (default: TERM)
+        -s      Don't display PIDs
+        -k      Kill found processes
+        -SIGNAL Signal to send (default: KILL)
 */
         /* Handle -SIGNAL. Oh my... */
-        killsig = SIGTERM;
+        killsig = SIGKILL; /* yes, the default is not SIGTERM */
         pp = argv;
         while (*++pp) {
                 char *arg = *pp;
@@ -313,33 +278,54 @@ Find processes which use FILEs or PORTs
                 break;
         }
 
+        opt_complementary = "-1"; /* at least one param */
         opt = getopt32(argv, OPTION_STRING);
         argv += optind;
 
-        ilist = NULL;
         pp = argv;
         while (*pp) {
-                char *proto = parse_net_arg(*pp, &port);
-                if (proto) { /* PORT/PROTO */
-                        ilist = scan_proc_net(proto, port, ilist);
-                        free(proto);
+                char *path = parse_net_arg(*pp, &port);
+                if (path) { /* PORT/PROTO */
+                        scan_proc_net(path, port);
+                        free(path);
                 } else { /* FILE */
-                        if (!file_to_dev_inode(*pp, &dev, &inode))
-                                bb_perror_msg_and_die("can't open '%s'", *pp);
-                        ilist = add_inode(ilist, dev, inode);
+                        xstat(*pp, &st);
+                        add_inode(&st);
                 }
                 pp++;
         }
 
-        plist = scan_proc_pids(ilist); /* changes dir to "/proc" */
+        scan_proc_pids(); /* changes dir to "/proc" */
 
-        if (!plist)
-                return EXIT_FAILURE;
-        success = 1;
-        if (opt & OPT_KILL) {
-                success = kill_pid_list(plist, killsig);
-        } else if (!(opt & OPT_SILENT)) {
-                success = print_pid_list(plist);
+        mypid = getpid();
+        plist = G.pid_list_head;
+        while (1) {
+                if (!plist)
+                        return EXIT_FAILURE;
+                if (plist->pid != mypid)
+                        break;
+                plist = plist->next;
         }
-        return (success != 1); /* 0 == success */
+
+        exitcode = EXIT_SUCCESS;
+        do {
+                if (plist->pid != mypid) {
+                        if (opt & OPT_KILL) {
+                                if (kill(plist->pid, killsig) != 0) {
+                                        bb_perror_msg("kill pid %u", (unsigned)plist->pid);
+                                        exitcode = EXIT_FAILURE;
+                                }
+                        }
+                        if (!(opt & OPT_SILENT)) {
+                                printf("%u ", (unsigned)plist->pid);
+                        }
+                }
+                plist = plist->next;
+        } while (plist);
+
+        if (!(opt & (OPT_SILENT))) {
+                bb_putchar('\n');
+        }
+
+        return exitcode;
 }