From 1fd0c9b0e1f27098f9bf86e86285335e640317a5 Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Fri, 15 Oct 2021 22:39:17 +0200 Subject: util, pasta: Don't read() and lseek() every single line in read_line() ...periodically checking bound ports becomes quite expensive otherwise. Signed-off-by: Stefano Brivio --- util.c | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-) (limited to 'util.c') diff --git a/util.c b/util.c index 0a05ffb..016749c 100644 --- a/util.c +++ b/util.c @@ -368,8 +368,8 @@ int bitmap_isset(uint8_t *map, int bit) } /** - * line_read() - Same as fgets(), without using heap, a file instead of a stream - * @buf: Read buffer + * line_read() - Similar to fgets(), no heap usage, a file instead of a stream + * @buf: Read buffer: on non-empty string, use that instead of reading * @len: Maximum line length * @fd: File descriptor for reading * @@ -377,14 +377,31 @@ int bitmap_isset(uint8_t *map, int bit) */ char *line_read(char *buf, size_t len, int fd) { + int n, do_read = !*buf; char *p; - int n; + + if (!do_read) { + char *nl; + + buf[len - 1] = 0; + if (!strlen(buf)) + return NULL; + + p = buf + strlen(buf) + 1; + + if (!(nl = strchr(p, '\n'))) + return NULL; + *nl = 0; + + return memmove(buf, p, len - (p - buf)); + } n = read(fd, buf, --len); if (n <= 0) return NULL; buf[len] = 0; + if (!(p = strchr(buf, '\n'))) return buf; @@ -393,6 +410,7 @@ char *line_read(char *buf, size_t len, int fd) return buf; lseek(fd, (p - buf) - n + 1, SEEK_CUR); + return buf; } @@ -404,7 +422,7 @@ char *line_read(char *buf, size_t len, int fd) */ void procfs_scan_listen(char *name, uint8_t *map, uint8_t *exclude) { - char line[200], path[PATH_MAX]; + char line[BUFSIZ], path[PATH_MAX]; unsigned long port; unsigned int state; int fd; @@ -413,6 +431,7 @@ void procfs_scan_listen(char *name, uint8_t *map, uint8_t *exclude) if ((fd = open(path, O_RDONLY)) < 0) return; + *line = 0; line_read(line, sizeof(line), fd); while (line_read(line, sizeof(line), fd)) { if (sscanf(line, "%*u: %*x:%lx %*x:%*x %x", &port, &state) != 2) -- cgit v1.2.3