9dc526d0f
Denys Vlasenko
2015-07-31
Subject
less: improve regular file detection in line counting code
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Commit Diff GitHub →
miscutils/less.c+28 -19
| @@ -165,12 +165,6 @@ enum { | |
| enum { pattern_valid = 0 }; | |
| #endif | |
| - | enum { |
| - | READING_FILE = -1, |
| - | READING_STDIN = -2, |
| - | READING_NONREG = -3 |
| - | }; |
| - | |
| struct globals { | |
| int cur_fline; /* signed */ | |
| int kbd_fd; /* fd to get input from */ | |
| @@ -195,7 +189,10 @@ struct globals { | |
| char *filename; | |
| char **files; | |
| #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 | |
| #if ENABLE_FEATURE_LESS_MARKS | |
| unsigned num_marks; | |
| @@ -622,14 +619,29 @@ static void update_num_lines(void) | |
| char buf[4096]; | |
| /* only do this for regular files */ | |
| - | if (num_lines == READING_FILE) { |
| + | if (num_lines != NOT_REGULAR_FILE) { |
| 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) { | |
| /* somebody stole my file! */ | |
| - | num_lines = READING_NONREG; |
| + | num_lines = NOT_REGULAR_FILE; |
| 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) { | |
| for (i = 0; i < len; ++i) { | |
| if (buf[i] == '\n' && ++count == MAXLINES) | |
| @@ -638,6 +650,7 @@ static void update_num_lines(void) | |
| } | |
| done: | |
| num_lines = count; | |
| + | do_close: |
| close(fd); | |
| } | |
| } | |
| @@ -991,18 +1004,17 @@ static void buffer_lineno(int lineno) | |
| static void open_file_and_read_lines(void) | |
| { | |
| if (filename) { | |
| + | xmove_fd(xopen(filename, O_RDONLY), STDIN_FILENO); |
| #if ENABLE_FEATURE_LESS_FLAGS | |
| - | struct stat stbuf; |
| - | |
| - | xstat(filename, &stbuf); |
| - | if (!S_ISREG(stbuf.st_mode)) |
| - | num_lines = READING_NONREG; |
| + | num_lines = REOPEN_AND_COUNT; |
| #endif | |
| - | xmove_fd(xopen(filename, O_RDONLY), STDIN_FILENO); |
| } else { | |
| /* "less" with no arguments in argv[] */ | |
| /* For status line only */ | |
| filename = xstrdup(bb_msg_standard_input); | |
| + | #if ENABLE_FEATURE_LESS_FLAGS |
| + | num_lines = REOPEN_STDIN; |
| + | #endif |
| } | |
| readpos = 0; | |
| readeof = 0; | |
| @@ -1026,9 +1038,6 @@ static void reinitialize(void) | |
| max_fline = -1; | |
| cur_fline = 0; | |
| max_lineno = 0; | |
| - | #if ENABLE_FEATURE_LESS_FLAGS |
| - | num_lines = filename ? READING_FILE : READING_STDIN; |
| - | #endif |
| open_file_and_read_lines(); | |
| #if ENABLE_FEATURE_LESS_ASK_TERMINAL | |
| if (G.winsize_err) | |