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authorRon Yorston2015-07-24 14:28:08 +0100
committerDenys Vlasenko2015-07-31 16:22:07 +0200
commit70b84be9e85969491e542cecc3ae28fa7558a7ec (patch)
tree15b5b57b0dd60215e00e0d586ad744452b819026
parent159e032bf4cd24535e57daaf29a381b0d5163368 (diff)
downloadbusybox-70b84be9e85969491e542cecc3ae28fa7558a7ec.zip
busybox-70b84be9e85969491e542cecc3ae28fa7558a7ec.tar.gz
less: rearrange detection of non-regular files
Move the code to detect non-regular files to the point where the file is being opened. If num_lines == READING_FILE guarantees that the file is regular. Detect when a file becomes unreadable between it first being opened and the call to update_num_lines. Mark the file as being non-regular so we don't try that again. function old new delta reinitialize 197 245 +48 update_num_lines 159 127 -32 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/1 up/down: 48/-32) Total: 16 bytes Signed-off-by: Ron Yorston <rmy@pobox.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--miscutils/less.c23
1 files changed, 15 insertions, 8 deletions
diff --git a/miscutils/less.c b/miscutils/less.c
index 8fd0874..91a933a 100644
--- a/miscutils/less.c
+++ b/miscutils/less.c
@@ -167,7 +167,8 @@ enum { pattern_valid = 0 };
enum {
READING_FILE = -1,
- READING_STDIN = -2
+ READING_STDIN = -2,
+ READING_NONREG = -3
};
struct globals {
@@ -615,15 +616,16 @@ static void update_num_lines(void)
int count, fd;
ssize_t len, i;
char buf[4096];
- struct stat stbuf;
+ /* only do this for regular files */
if (num_lines == READING_FILE) {
count = 0;
fd = open(filename, O_RDONLY);
- if (fd < 0)
- goto skip;
- if (fstat(fd, &stbuf) != 0 || !S_ISREG(stbuf.st_mode))
- goto do_close;
+ if (fd < 0) {
+ /* somebody stole my file! */
+ num_lines = READING_NONREG;
+ return;
+ }
while ((len = safe_read(fd, buf, sizeof(buf))) > 0) {
for (i = 0; i < len; ++i) {
if (buf[i] == '\n' && ++count == MAXLINES)
@@ -632,9 +634,7 @@ static void update_num_lines(void)
}
done:
num_lines = count;
- do_close:
close(fd);
- skip: ;
}
}
@@ -943,6 +943,13 @@ static void buffer_line(int linenum)
static void open_file_and_read_lines(void)
{
if (filename) {
+#if ENABLE_FEATURE_LESS_FLAGS
+ struct stat stbuf;
+
+ xstat(filename, &stbuf);
+ if (!S_ISREG(stbuf.st_mode))
+ num_lines = READING_NONREG;
+#endif
xmove_fd(xopen(filename, O_RDONLY), STDIN_FILENO);
} else {
/* "less" with no arguments in argv[] */