138ec0e0d
Denys Vlasenko
2026-02-27
Subject
less: unbreak EAGAIN propagation
Binary
No binary (build failed)
Architecture & Compiler Flags
gcc -Wp,-MD,applets/.usage.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -Iinclude -Iinclude -o applets/usage applets/usage.c
Build Log
(log yok)
Commit Diff GitHub →
miscutils/less.c+12 -6
| @@ -469,7 +469,7 @@ static int at_end(void) | |
| */ | |
| static void read_lines(void) | |
| { | |
| - | int ndelay_set, fdflags; |
| + | int ndelay_set, eagain, fdflags; |
| char *current_line, *p; | |
| int w = width; | |
| char last_terminated = terminated; | |
| @@ -502,7 +502,8 @@ static void read_lines(void) | |
| // "less FILE": can set O_NONBLOCK on open. | |
| // "true | less": can't. | |
| // " { less; cat; } <FILE": can't. And must not confuse cat. | |
| - | ndelay_set = -1; // "don't know whetherstdin is nonblocking" |
| + | ndelay_set = -1; // "don't know whether stdin is nonblocking" |
| + | eagain = 0; |
| while (1) { /* read lines until we reach cur_fline or wanted_match */ | |
| *p = '\0'; | |
| @@ -525,13 +526,13 @@ static void read_lines(void) | |
| // This has the effect that e.g. PageDown on a regular file | |
| // where we already reached EOF *will try reading anyway*, | |
| // if the file is a growing log file, less *will* show the new data. | |
| - | G.eof_error_ok = safe_read(STDIN_FILENO, readbuf, COMMON_BUFSIZE); |
| readpos = 0; | |
| + | G.eof_error_ok = safe_read(STDIN_FILENO, readbuf, COMMON_BUFSIZE); |
| read_size = G.eof_error_ok; | |
| if (G.eof_error_ok <= 0) { | |
| - | read_size = 0; // -1 would be seen as UINT_MAX, prevent |
| if (G.eof_error_ok < 0 && errno == EAGAIN) | |
| - | G.eof_error_ok = 1; // "neither EOF nor error" |
| + | eagain = 1; |
| + | read_size = 0; // -1 would be seen as UINT_MAX, prevent |
| goto reached_eof; | |
| } | |
| } | |
| @@ -626,8 +627,13 @@ static void read_lines(void) | |
| break; | |
| #endif | |
| } | |
| - | if (G.eof_error_ok <= 0) /* EOF or error? */ |
| + | if (G.eof_error_ok <= 0) { /* EOF or error? */ |
| + | if (eagain) { |
| + | G.eof_error_ok = 1; // "neither EOF nor error: stdin not ready" |
| + | //^^^ needed to make main loop's poll() check stdin |
| + | } |
| break; | |
| + | } |
| max_fline++; | |
| current_line = ((char*)xmalloc(w + 5)) + 4; | |
| p = current_line; | |