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authorGravatar Denis Vlasenko <vda.linux@googlemail.com>2008-04-20 14:45:43 +0000
committerGravatar Denis Vlasenko <vda.linux@googlemail.com>2008-04-20 14:45:43 +0000
commit0a1446275d88946734417ed96a3c0f1d7ea969e4 (patch)
tree577ea76080a5251ad54418c2831213e64e02563d
parentfe493479e2814f25edc270a5605678adbc90086a (diff)
downloadbusybox-0a1446275d88946734417ed96a3c0f1d7ea969e4.tar.gz
busybox-0a1446275d88946734417ed96a3c0f1d7ea969e4.tar.bz2
xmalloc_open_read_close: use fstat to get file size (instead of lseek).
by Joakim Tjernlund <Joakim.Tjernlund AT transmode.se> function old new delta xmalloc_open_read_close 190 181 -9
-rw-r--r--libbb/read.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/libbb/read.c b/libbb/read.c
index e5f140f3b..288358d79 100644
--- a/libbb/read.c
+++ b/libbb/read.c
@@ -211,6 +211,48 @@ void *xmalloc_open_read_close(const char *filename, size_t *sizep)
size_t size;
int fd;
off_t len;
+ struct stat st;
+
+ fd = open(filename, O_RDONLY);
+ if (fd < 0)
+ return NULL;
+
+ st.st_size = 0; /* in case fstat fail, define to 0 */
+ fstat(fd, &st);
+ /* /proc/N/stat files report len 0 here */
+ /* In order to make such files readable, we add small const */
+ len = st.st_size | 0x3ff; /* read only 1k on unseekable files */
+ size = sizep ? *sizep : INT_MAX;
+ if (len < size)
+ size = len;
+ buf = xmalloc(size + 1);
+ size = read_close(fd, buf, size);
+ if ((ssize_t)size < 0) {
+ free(buf);
+ return NULL;
+ }
+ xrealloc(buf, size + 1);
+ buf[size] = '\0';
+
+ if (sizep)
+ *sizep = size;
+ return buf;
+}
+
+#ifdef USING_LSEEK_TO_GET_SIZE
+/* Alternatively, file size can be obtained by lseek to the end.
+ * The code is slightly bigger. Retained in case fstat approach
+ * will not work for some weird cases (/proc, block devices, etc).
+ * (NB: lseek also can fail to work for some weird files) */
+
+// Read (potentially big) files in one go. File size is estimated by
+// lseek to end.
+void *xmalloc_open_read_close(const char *filename, size_t *sizep)
+{
+ char *buf;
+ size_t size;
+ int fd;
+ off_t len;
fd = open(filename, O_RDONLY);
if (fd < 0)
@@ -240,6 +282,7 @@ void *xmalloc_open_read_close(const char *filename, size_t *sizep)
*sizep = size;
return buf;
}
+#endif
void *xmalloc_xopen_read_close(const char *filename, size_t *sizep)
{