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less: improve regular file detection in line counting code

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2015-07-31 16:42:20 +02:00
parent 1ecb996fd2
commit 9dc526d0f9
1 changed files with 29 additions and 20 deletions
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49
miscutils/less.c
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@ -165,12 +165,6 @@ enum {
enum { pattern_valid = 0 }; enum { pattern_valid = 0 };
#endif #endif
enum {
READING_FILE = -1,
READING_STDIN = -2,
READING_NONREG = -3
};
struct globals { struct globals {
int cur_fline; /* signed */ int cur_fline; /* signed */
int kbd_fd; /* fd to get input from */ int kbd_fd; /* fd to get input from */
@ -195,7 +189,10 @@ struct globals {
char *filename; char *filename;
char **files; char **files;
#if ENABLE_FEATURE_LESS_FLAGS #if ENABLE_FEATURE_LESS_FLAGS
int num_lines; /* input source if < 0, line count if >= 0 */ int num_lines; /* a flag if < 0, line count if >= 0 */
# define REOPEN_AND_COUNT (-1)
# define REOPEN_STDIN (-2)
# define NOT_REGULAR_FILE (-3)
#endif #endif
#if ENABLE_FEATURE_LESS_MARKS #if ENABLE_FEATURE_LESS_MARKS
unsigned num_marks; unsigned num_marks;
@ -622,14 +619,29 @@ static void update_num_lines(void)
char buf[4096]; char buf[4096];
/* only do this for regular files */ /* only do this for regular files */
if (num_lines == READING_FILE) { if (num_lines != NOT_REGULAR_FILE) {
count = 0; count = 0;
fd = open(filename, O_RDONLY); fd = open("/proc/self/fd/0", O_RDONLY);
if (fd < 0 && num_lines == REOPEN_AND_COUNT) {
/* "filename" is valid only if REOPEN_AND_COUNT */
fd = open(filename, O_RDONLY);
}
if (fd < 0) { if (fd < 0) {
/* somebody stole my file! */ /* somebody stole my file! */
num_lines = READING_NONREG; num_lines = NOT_REGULAR_FILE;
return; return;
} }
#if ENABLE_FEATURE_LESS_FLAGS
{
struct stat stbuf;
if (fstat(fd, &stbuf) != 0
|| !S_ISREG(stbuf.st_mode)
) {
num_lines = NOT_REGULAR_FILE;
goto do_close;
}
}
#endif
while ((len = safe_read(fd, buf, sizeof(buf))) > 0) { while ((len = safe_read(fd, buf, sizeof(buf))) > 0) {
for (i = 0; i < len; ++i) { for (i = 0; i < len; ++i) {
if (buf[i] == '\n' && ++count == MAXLINES) if (buf[i] == '\n' && ++count == MAXLINES)
@ -638,6 +650,7 @@ static void update_num_lines(void)
} }
done: done:
num_lines = count; num_lines = count;
do_close:
close(fd); close(fd);
} }
} }
@ -991,18 +1004,17 @@ static void buffer_lineno(int lineno)
static void open_file_and_read_lines(void) static void open_file_and_read_lines(void)
{ {
if (filename) { 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); xmove_fd(xopen(filename, O_RDONLY), STDIN_FILENO);
#if ENABLE_FEATURE_LESS_FLAGS
num_lines = REOPEN_AND_COUNT;
#endif
} else { } else {
/* "less" with no arguments in argv[] */ /* "less" with no arguments in argv[] */
/* For status line only */ /* For status line only */
filename = xstrdup(bb_msg_standard_input); filename = xstrdup(bb_msg_standard_input);
#if ENABLE_FEATURE_LESS_FLAGS
num_lines = REOPEN_STDIN;
#endif
} }
readpos = 0; readpos = 0;
readeof = 0; readeof = 0;
@ -1026,9 +1038,6 @@ static void reinitialize(void)
max_fline = -1; max_fline = -1;
cur_fline = 0; cur_fline = 0;
max_lineno = 0; max_lineno = 0;
#if ENABLE_FEATURE_LESS_FLAGS
num_lines = filename ? READING_FILE : READING_STDIN;
#endif
open_file_and_read_lines(); open_file_and_read_lines();
#if ENABLE_FEATURE_LESS_ASK_TERMINAL #if ENABLE_FEATURE_LESS_ASK_TERMINAL
if (G.winsize_err) if (G.winsize_err)