Made new xreadlink function for libbb and changed applets to use it instead of

readlink(2).

3 files changed, 38 insertions, 10 deletions

diff --git a/libbb/copy_file.c b/libbb/copy_file.c
index 2d18b6087..22684be74 100644
--- a/libbb/copy_file.c
+++ b/libbb/copy_file.c
@@ -196,19 +196,12 @@ int copy_file(const char *source, const char *dest, int flags)
 			return -1;
 		}
 	} else if (S_ISLNK(source_stat.st_mode)) {
-		int size;
-		char buf[BUFSIZ + 1];
-
-		if ((size = readlink(source, buf, BUFSIZ)) < 0) {
-			perror_msg("cannot read `%s'", source);
-			return -1;
-		}
-		buf[size] = '\0';
-
-		if (symlink(buf, dest) < 0) {
+		char *lpath = xreadlink(source);
+		if (symlink(lpath, dest) < 0) {
 			perror_msg("cannot create symlink `%s'", dest);
 			return -1;
 		}
+		free(lpath);
 
 #if (__GLIBC__ >= 2) && (__GLIBC_MINOR__ >= 1)
 		if (flags & FILEUTILS_PRESERVE_STATUS)
diff --git a/libbb/libbb.h b/libbb/libbb.h
index a53e647d3..d2f9a9567 100644
--- a/libbb/libbb.h
+++ b/libbb/libbb.h
@@ -217,6 +217,7 @@ int ask_confirmation(void);
 int klogctl(int type, char * b, int len);
 
 char *xgetcwd(char *cwd);
+char *xreadlink(const char *path);
 char *concat_path_file(const char *path, const char *filename);
 int last_char_is(const char *s, const int c);
 
diff --git a/libbb/xreadlink.c b/libbb/xreadlink.c
new file mode 100644
index 000000000..66f63b883
--- /dev/null
+++ b/libbb/xreadlink.c
@@ -0,0 +1,34 @@
+/*
+ *  xreadlink.c - safe implementation of readlink
+ */
+
+#include <stdio.h>
+
+/*
+ * NOTE: This function returns a malloced char* that you will have to free
+ * yourself. You have been warned.
+ */
+
+#include <unistd.h>
+#include "libbb.h"
+
+extern char *xreadlink(const char *path)
+{                       
+	static const int GROWBY = 80; /* how large we will grow strings by */
+
+	char *buf = NULL;   
+	int bufsize = 0, readsize = 0;
+
+	do {
+		buf = xrealloc(buf, bufsize += GROWBY);
+		readsize = readlink(path, buf, bufsize); /* 1st try */
+		if (readsize == -1)
+			perror_msg("%s:%s", applet_name, path);
+	}           
+	while (bufsize < readsize + 1);
+
+	buf[readsize] = '\0';
+
+	return buf;
+}       
+