X-Git-Url: https://ruderich.org/simon/gitweb/?p=coloredstderr%2Fcoloredstderr.git;a=blobdiff_plain;f=src%2Ftrackfds.h;h=00b3b6e3b55da47e7c66453e609e6b7754a6071d;hp=5896cbb4ee3eb223db010131253bb609d45de774;hb=f30dbbd26d18e3014762ccc37b8e5ab65b596b35;hpb=feff94de6be535f17f06e3c135366b33ab9c0ca3

diff --git a/src/trackfds.h b/src/trackfds.h
index 5896cbb..00b3b6e 100644
--- a/src/trackfds.h
+++ b/src/trackfds.h
@@ -20,26 +20,55 @@
 #ifndef TRACKFDS_H
 #define TRACKFDS_H 1
 
-/* List of tracked file descriptors. */
-static int *tracked_fds;
+/* Array of tracked file descriptors. Used for fast lookups for the normally
+ * used file descriptors (0 <= fd < TRACKFDS_STATIC_COUNT). */
+static int tracked_fds[TRACKFDS_STATIC_COUNT];
+
+/* List of tracked file descriptors >= TRACKFDS_STATIC_COUNT. */
+static int *tracked_fds_list;
 /* Current number of items in the list. */
-static size_t tracked_fds_count;
+static size_t tracked_fds_list_count;
 /* Allocated items, used to reduce realloc()s. */
-static size_t tracked_fds_space;
+static size_t tracked_fds_list_space;
 
 
 #ifdef DEBUG
 static void tracked_fds_debug(void) {
-    debug("    tracked_fds: %d/%d\t\t[%d]\n", tracked_fds_count,
-                                              tracked_fds_space,
-                                              getpid());
     size_t i;
-    for (i = 0; i < tracked_fds_count; i++) {
-        debug("    tracked_fds[%d]: %d\n", i, tracked_fds[i]);
+
+    for (i = 0; i < TRACKFDS_STATIC_COUNT; i++) {
+        if (tracked_fds[i]) {
+            debug("    tracked_fds[%d]: %d\n", i, tracked_fds[i]);
+        }
+    }
+    debug("    tracked_fds_list: %d/%d\t[%d]\n", tracked_fds_list_count,
+                                                 tracked_fds_list_space,
+                                                 getpid());
+    for (i = 0; i < tracked_fds_list_count; i++) {
+        debug("    tracked_fds_list[%d]: %d\n", i, tracked_fds_list[i]);
     }
 }
 #endif
 
+static int init_tracked_fds_list(size_t count) {
+    assert(count > 0);
+
+    /* Reduce reallocs. */
+    count += TRACKFDS_REALLOC_STEP;
+
+    tracked_fds_list = malloc(count * sizeof(*tracked_fds_list));
+    if (!tracked_fds_list) {
+#ifdef WARNING
+        warning("malloc(tracked_fds_list, %d) failed [%d]\n",
+                count * sizeof(*tracked_fds_list), getpid());
+#endif
+        return 0;
+    }
+
+    tracked_fds_list_space = count;
+    return 1;
+}
+
 /* Load tracked file descriptors from the environment. The environment is used
  * to pass the information to child processes.
  *
@@ -49,10 +78,12 @@ static void init_from_environment(void) {
 #ifdef DEBUG
     debug("init_from_environment()\t\t[%d]\n", getpid());
 #endif
-    const char *env;
+    char const *env;
+
+    int saved_errno = errno;
 
     initialized = 1;
-    tracked_fds_count = 0;
+    tracked_fds_list_count = 0;
 
     /* If ENV_NAME_FORCE_WRITE is set and not empty, allow writes to a non-tty
      * device. Use with care! Mainly used for the test suite. */
@@ -63,8 +94,12 @@ static void init_from_environment(void) {
 
     env = getenv(ENV_NAME_FDS);
     if (!env) {
+        errno = saved_errno;
         return;
     }
+#ifdef DEBUG
+    debug("  getenv(\"%s\"): \"%s\"\n", ENV_NAME_FDS, env);
+#endif
     /* Environment is read-only. */
     char env_copy[strlen(env) + 1];
     strcpy(env_copy, env);
@@ -77,17 +112,11 @@ static void init_from_environment(void) {
             count++;
         }
     }
-    tracked_fds_space = count + TRACKFDS_REALLOC_STEP;
-
-    tracked_fds = malloc(tracked_fds_space * sizeof(*tracked_fds));
-    if (!tracked_fds) {
-        return;
-    }
 
     size_t i = 0;
 
     /* Parse file descriptor numbers from environment string and store them as
-     * integers in tracked_fds. */
+     * integers in tracked_fds and tracked_fds_list. */
     char *last;
     for (x = env_copy, last = env_copy; *x; x++) {
         if (*x != ',') {
@@ -104,39 +133,83 @@ static void init_from_environment(void) {
         }
 
         *x = 0;
-        tracked_fds[i++] = atoi(last);
 
+        int fd = atoi(last);
+        if (fd < TRACKFDS_STATIC_COUNT) {
+            tracked_fds[fd] = 1;
+        } else {
+            if (!tracked_fds_list) {
+                /* Pessimistic count estimate, but allocating a few more
+                 * elements doesn't hurt. */
+                if (!init_tracked_fds_list(count)) {
+                    /* Couldn't allocate memory, skip this entry. */
+                    goto next;
+                }
+            }
+            tracked_fds_list[i++] = fd;
+#ifdef DEBUG
+            debug("  large fd: %d\n", fd);
+#endif
+        }
+
+next:
         last = x + 1;
     }
 
-    tracked_fds_count = count;
+    tracked_fds_list_count = i;
 
 #ifdef DEBUG
     tracked_fds_debug();
 #endif
+
+    errno = saved_errno;
 }
 
+static char *update_environment_buffer_entry(char *x, int fd) {
+    assert(fd >= 0);
+
+    int length = snprintf(x, 10 + 1, "%d", fd);
+    if (length >= 10 + 1 || length <= 0 /* shouldn't happen */) {
+        /* Integer too big to fit the buffer, skip it. */
+#ifdef WARNING
+        warning("update_environment_buffer_entry(): truncated fd: %d [%d]\n",
+                fd, getpid());
+#endif
+        return x;
+    }
+
+    /* Write comma after number. */
+    x += length;
+    *x++ = ',';
+    /* Make sure the string is always zero terminated. */
+    *x = 0;
+
+    return x;
+}
 static void update_environment_buffer(char *x) {
+    assert(initialized);
+
     size_t i;
-    for (i = 0; i < tracked_fds_count; i++) {
-        int length = snprintf(x, 10 + 1, "%d", tracked_fds[i]);
-        if (length >= 10 + 1) {
-            /* Integer too big to fit the buffer, skip it. */
-            continue;
+    for (i = 0; i < TRACKFDS_STATIC_COUNT; i++) {
+        if (tracked_fds[i]) {
+            x = update_environment_buffer_entry(x, (int)i);
         }
-
-        /* Write comma after number. */
-        x += length;
-        *x++ = ',';
-        /* Make sure the string is always zero terminated. */
-        *x = 0;
+    }
+    for (i = 0; i < tracked_fds_list_count; i++) {
+        x = update_environment_buffer_entry(x, tracked_fds_list[i]);
     }
 }
 inline static size_t update_environment_buffer_size(void) {
-    /* An integer (32-bit) has at most 10 digits, + 1 for the comma after each
+    assert(initialized);
+
+    /* Use the maximum count (TRACKFDS_STATIC_COUNT) of used descriptors
+     * because it's simple and small enough not to be a problem.
+     *
+     * An integer (32-bit) has at most 10 digits, + 1 for the comma after each
      * number. Bigger file descriptors (which shouldn't occur in reality) are
      * skipped. */
-    return tracked_fds_count * (10 + 1) + 1 /* to fit '\0' */;
+    return (TRACKFDS_STATIC_COUNT + tracked_fds_list_count)
+               * (10 + 1) + 1 /* to fit '\0' */;
 }
 static void update_environment(void) {
 #ifdef DEBUG
@@ -155,7 +228,7 @@ static void update_environment(void) {
     update_environment_buffer(env);
 
 #if 0
-    debug("    setenv('%s', '%s', 1)\n", ENV_NAME_FDS, env);
+    debug("    setenv(\"%s\", \"%s\", 1)\n", ENV_NAME_FDS, env);
 #endif
 
     setenv(ENV_NAME_FDS, env, 1 /* overwrite */);
@@ -164,24 +237,41 @@ static void update_environment(void) {
 
 
 static void tracked_fds_add(int fd) {
-    if (tracked_fds_count >= tracked_fds_space) {
-        size_t new_space = tracked_fds_space + TRACKFDS_REALLOC_STEP;
-        int *tmp = realloc(tracked_fds, sizeof(*tracked_fds) * new_space);
+    assert(fd >= 0);
+
+    if (fd < TRACKFDS_STATIC_COUNT) {
+        tracked_fds[fd] = 1;
+#if 0
+        debug("tracked_fds_add(): %-3d\t\t[%d]\n", fd, getpid());
+        tracked_fds_debug();
+#endif
+        return;
+    }
+
+    if (tracked_fds_list_count >= tracked_fds_list_space) {
+        int saved_errno = errno;
+
+        size_t new_space = tracked_fds_list_space + TRACKFDS_REALLOC_STEP;
+        int *tmp = realloc(tracked_fds_list,
+                           sizeof(*tracked_fds_list) * new_space);
         if (!tmp) {
             /* We can do nothing, just ignore the error. We made sure not to
              * destroy our state, so the new descriptor is ignored without any
              * other consequences. */
-#ifdef DEBUG
-            debug("realloc(tracked_fds, %zu) failed! [%d]\n",
-                  sizeof(*tracked_fds) * new_space, getpid());
+#ifdef WARNING
+            warning("realloc(tracked_fds_list, %zu) failed! [%d]\n",
+                    sizeof(*tracked_fds_list) * new_space, getpid());
 #endif
+            errno = saved_errno;
             return;
         }
-        tracked_fds = tmp;
-        tracked_fds_space = new_space;
+        errno = saved_errno;
+
+        tracked_fds_list = tmp;
+        tracked_fds_list_space = new_space;
     }
 
-    tracked_fds[tracked_fds_count++] = fd;
+    tracked_fds_list[tracked_fds_list_count++] = fd;
 
 #ifdef DEBUG
     debug("tracked_fds_add(): %-3d\t\t[%d]\n", fd, getpid());
@@ -189,15 +279,28 @@ static void tracked_fds_add(int fd) {
 #endif
 }
 static int tracked_fds_remove(int fd) {
+    assert(fd >= 0);
+
+    if (fd < TRACKFDS_STATIC_COUNT) {
+        int old_value = tracked_fds[fd];
+        tracked_fds[fd] = 0;
+
+#if 0
+        debug("tracked_fds_remove(): %-3d\t[%d]\n", fd, getpid());
+        tracked_fds_debug();
+#endif
+        return old_value; /* Found vs. not found. */
+    }
+
     size_t i;
-    for (i = 0; i < tracked_fds_count; i++) {
-        if (fd != tracked_fds[i]) {
+    for (i = 0; i < tracked_fds_list_count; i++) {
+        if (fd != tracked_fds_list[i]) {
             continue;
         }
 
-        memmove(tracked_fds + i, tracked_fds + i + 1,
-                sizeof(*tracked_fds) * (tracked_fds_count - i - 1));
-        tracked_fds_count--;
+        memmove(tracked_fds_list + i, tracked_fds_list + i + 1,
+                sizeof(*tracked_fds_list) * (tracked_fds_list_count - i - 1));
+        tracked_fds_list_count--;
 
 #ifdef DEBUG
         debug("tracked_fds_remove(): %-3d\t[%d]\n", fd, getpid());
@@ -211,10 +314,36 @@ static int tracked_fds_remove(int fd) {
     /* Not found. */
     return 0;
 }
-static int tracked_fds_find(int fd) {
+
+static int tracked_fds_find_slow(int fd) noinline;
+/*
+ * tracked_fds_find() is called for each hook call and should be as fast as
+ * possible. As most file descriptors are < TRACKFDS_STATIC_COUNT, force the
+ * compiler to inline that part which is almost exclusively used.
+ *
+ * Inlining tracked_fds_add()/tracked_fds_remove() isn't worth the effort as
+ * they are not called often enough.
+ */
+inline static int tracked_fds_find(int fd) always_inline;
+inline static int tracked_fds_find(int fd) {
+    assert(fd >= 0);
+
+    if (fd < TRACKFDS_STATIC_COUNT) {
+        return tracked_fds[fd];
+    }
+
+    return tracked_fds_find_slow(fd);
+}
+static int tracked_fds_find_slow(int fd) {
+    assert(initialized);
+
+    if (tracked_fds_list_count == 0) {
+        return 0;
+    }
+
     size_t i;
-    for (i = 0; i < tracked_fds_count; i++) {
-        if (fd == tracked_fds[i]) {
+    for (i = 0; i < tracked_fds_list_count; i++) {
+        if (fd == tracked_fds_list[i]) {
             return 1;
         }
     }