From cf18010ca966aa2be06e0466aeb78b54d15957e2 Mon Sep 17 00:00:00 2001
From: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
Date: Mon, 26 May 2008 15:12:01 +0000
Subject: - use mmap instead of allocating hundreds of megabytes of RAM. +39b

---
 modutils/depmod.c | 63 +++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 43 insertions(+), 20 deletions(-)

(limited to 'modutils/depmod.c')

diff --git a/modutils/depmod.c b/modutils/depmod.c
index 489a0330e..5d51ba450 100644
--- a/modutils/depmod.c
+++ b/modutils/depmod.c
@@ -11,6 +11,12 @@
 #include <libbb.h>
 #include <sys/utsname.h> /* uname() */
 
+/*
+ * Theory of operation:
+ * - iterate over all modules and record their full path
+ * - iterate over all modules looking for "depends=" entries
+ *   for each depends, look through our list of full paths and emit if found
+ */
 struct globals {
 	llist_t *lst;
 };
@@ -25,40 +31,56 @@ static int fill_lst(const char *modulename, struct stat ATTRIBUTE_UNUSED *sb,
 	return TRUE;
 }
 
-static int fileAction(const char *fname, struct stat ATTRIBUTE_UNUSED *sb,
+static int fileAction(const char *fname, struct stat *sb,
 					void *data, int ATTRIBUTE_UNUSED depth)
 {
-	size_t seen = 0;
-	size_t len = MAXINT(ssize_t);
-	void *the_module = xmalloc_open_read_close(fname, &len), *ptr = the_module;
-	const char *deps;
-	RESERVE_CONFIG_BUFFER(depends, 512);
-	RESERVE_CONFIG_BUFFER(buf1, 512);
-
-	memset(depends, 0, sizeof(depends));
+	size_t len = sb->st_size;
+	void *the_module, *ptr;
+	int fd;
+	char *depends, *deps;
 
+/*XXX: FIXME: does not handle compressed modules!
+ * There should be a function that looks at the extension and sets up
+ * open_transformer for us.
+ */
 	if (last_char_is(fname, 'o') == NULL) /* not a module */
-		goto done;
+		goto skip;
+
+	fd = xopen(fname, O_RDONLY);
+	the_module = mmap(NULL, len, PROT_READ, MAP_SHARED
+#if defined MAP_POPULATE
+						|MAP_POPULATE
+#endif
+						, fd, 0);
+	close(fd);
+	if (the_module == MAP_FAILED)
+		bb_perror_msg_and_die("mmap");
+
+	ptr = the_module;
+
 	fprintf((FILE*)data, "\n%s:", fname);
-//bb_info_msg("[%d] fname='%s'", (int)data, fname);
+//bb_info_msg("fname='%s'", fname);
 	do {
 		/* search for a 'd' */
-		ptr = memchr(ptr, 'd', len - seen);
+		ptr = memchr(ptr, 'd', len);
 		if (ptr == NULL) /* no d left, done */
+			goto done;
+		if (memcmp(ptr, "depends=", sizeof("depends=")-1) == 0)
 			break;
-		if (sscanf(ptr, "depends=%s", depends) == 1)
-			break;
-		seen = ++ptr - the_module;
+		len -= ++ptr - the_module;
 	} while (1);
+	deps = depends = strdup (ptr + sizeof("depends=")-1);
 //bb_info_msg(" depends='%s'", depends);
-	deps = depends;
 	while (*deps) {
 		llist_t * _lst = G.lst;
+		char *buf1;
+
 		ptr = strchr(deps, ',');
 		if (ptr != NULL)
 			*(char*)ptr = '\0';
 		/* remember the length of the current dependency plus eventual 0 byte */
 		len = strlen(deps) + (ptr != NULL);
+		buf1 = xmalloc(len + 3);
 		sprintf(buf1, "/%s.", deps); /* make sure we match the correct file */
 		while (_lst) {
 			ptr = strstr(_lst->data, buf1);
@@ -66,16 +88,17 @@ static int fileAction(const char *fname, struct stat ATTRIBUTE_UNUSED *sb,
 				break; /* found it */
 			_lst = _lst->link;
 		}
-		if (_lst && _lst->data) {
+		free(buf1);
+		if (_lst /*&& _lst->data*/) {
 //bb_info_msg("[%s] -> '%s'", deps, _lst->data);
 			fprintf((FILE*)data, " %s", _lst->data);
 			deps += len;
 		}
 	}
+	free(depends);
 done:
-	RELEASE_CONFIG_BUFFER(depends);
-	RELEASE_CONFIG_BUFFER(buf1);
-	free(the_module);
+	munmap(the_module, sb->st_size);
+skip:
 	return TRUE;
 }
 
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