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authorRob Landley <rob@landley.net>2012-08-25 14:25:22 -0500
committerRob Landley <rob@landley.net>2012-08-25 14:25:22 -0500
commit3a9241add947cb6d24b5de7a8927517426a78795 (patch)
treed122ab6570439cd6b17c7d73ed8d4e085e0b8a95 /toys/tail.c
parent689f095bc976417bf50810fe59a3b3ac32b21105 (diff)
downloadtoybox-3a9241add947cb6d24b5de7a8927517426a78795.tar.gz
Move commands into "posix", "lsb", and "other" menus/directories.
Diffstat (limited to 'toys/tail.c')
-rw-r--r--toys/tail.c232
1 files changed, 0 insertions, 232 deletions
diff --git a/toys/tail.c b/toys/tail.c
deleted file mode 100644
index 8783d6ba..00000000
--- a/toys/tail.c
+++ /dev/null
@@ -1,232 +0,0 @@
-/* vi: set sw=4 ts=4:
- *
- * tail.c - copy last lines from input to stdout.
- *
- * Copyright 2012 Timothy Elliott <tle@holymonkey.com>
- *
- * See http://www.opengroup.org/onlinepubs/009695399/utilities/tail.html
-
-USE_TAIL(NEWTOY(tail, "fc-n-", TOYFLAG_BIN))
-
-config TAIL
- bool "tail"
- default y
- help
- usage: tail [-n|c number] [-f] [file...]
-
- Copy last lines from files to stdout. If no files listed, copy from
- stdin. Filename "-" is a synonym for stdin.
-
- -n output the last X lines (default 10), +X counts from start.
- -c output the last X bytes, +X counts from start
- -f follow file, waiting for more data to be appended
-
-config TAIL_SEEK
- bool "tail seek support"
- default y
- depends on TAIL
- help
- This version uses lseek, which is faster on large files.
-*/
-
-#include "toys.h"
-
-DEFINE_GLOBALS(
- long lines;
- long bytes;
-
- int file_no;
-)
-
-#define TT this.tail
-
-#define FLAG_n 1
-#define FLAG_c 2
-#define FLAG_f 4
-
-struct line_list {
- struct line_list *next, *prev;
- char *data;
- int len;
-};
-
-static struct line_list *get_chunk(int fd, int len)
-{
- struct line_list *line = xmalloc(sizeof(struct line_list)+len);
-
- line->data = ((char *)line) + sizeof(struct line_list);
- line->len = readall(fd, line->data, len);
-
- if (line->len < 1) {
- free(line);
- return 0;
- }
-
- return line;
-}
-
-static void dump_chunk(void *ptr)
-{
- struct line_list *list = ptr;
- xwrite(1, list->data, list->len);
- free(list);
-}
-
-// Reading through very large files is slow. Using lseek can speed things
-// up a lot, but isn't applicable to all input (cat | tail).
-// Note: bytes and lines are negative here.
-static int try_lseek(int fd, long bytes, long lines)
-{
- struct line_list *list = 0, *temp;
- int flag = 0, chunk = sizeof(toybuf);
- ssize_t pos = lseek(fd, 0, SEEK_END);
-
- // If lseek() doesn't work on this stream, return now.
- if (pos<0) return 0;
-
- // Seek to the right spot, output data from there.
- if (bytes) {
- if (lseek(fd, bytes, SEEK_END)<0) lseek(fd, 0, SEEK_SET);
- xsendfile(fd, 1);
- return 1;
- }
-
- // Read from end to find enough lines, then output them.
-
- bytes = pos;
- while (lines && pos) {
- int offset;
-
- // Read in next chunk from end of file
- if (chunk>pos) chunk = pos;
- pos -= chunk;
- if (pos != lseek(fd, pos, SEEK_SET)) {
- perror_msg("seek failed");
- break;
- }
- if (!(temp = get_chunk(fd, chunk))) break;
- if (list) list->next = temp;
- list = temp;
-
- // Count newlines in this chunk.
- offset = list->len;
- while (offset--) {
- // If the last line ends with a newline, that one doesn't count.
- if (!flag) {
- flag++;
-
- continue;
- }
-
- // Start outputting data right after newline
- if (list->data[offset] == '\n' && !++lines) {
- offset++;
- list->data += offset;
- list->len -= offset;
-
- break;
- }
- }
- }
-
- // Output stored data
- llist_traverse(list, dump_chunk);
-
- // In case of -f
- lseek(fd, bytes, SEEK_SET);
- return 1;
-}
-
-// Called for each file listed on command line, and/or stdin
-static void do_tail(int fd, char *name)
-{
- long bytes = TT.bytes, lines = TT.lines;
-
- if (toys.optc > 1) {
- if (TT.file_no++) xputc('\n');
- xprintf("==> %s <==\n", name);
- }
-
- // Are we measuring from the end of the file?
-
- if (bytes<0 || lines<0) {
- struct line_list *list = 0, *new;
-
- // The slow codepath is always needed, and can handle all input,
- // so make lseek support optional.
- if (CFG_TAIL_SEEK && try_lseek(fd, bytes, lines));
-
- // Read data until we run out, keep a trailing buffer
- else for (;;) {
- int len, count;
- char *try;
-
- if (!(new = get_chunk(fd, sizeof(toybuf)))) break;
- // append in order
- dlist_add_nomalloc((struct double_list **)&list,
- (struct double_list *)new);
-
- // Measure new chunk, discarding extra data from buffer
- len = new->len;
- try = new->data;
- for (count=0; count<len; count++) {
- if ((toys.optflags & FLAG_c) && bytes) {
- bytes++;
- continue;
- }
-
- if (lines) {
- if(try[count] != '\n' && count != len-1) continue;
- if (lines<0) {
- if (!++lines) ++lines;
- continue;
- }
- }
-
- // Time to discard data; given that bytes and lines were
- // nonzero coming in, we can't discard too much if we're
- // measuring right.
- do {
- char c = *(list->data++);
- if (!(--list->len)) {
- struct line_list *next = list->next;
- list->prev->next = next;
- list->next->prev = list->prev;
- free(list);
- list = next;
- }
- if (c == '\n') break;
- } while (lines);
- }
- }
-
- // Output/free the buffer.
- llist_traverse(list, dump_chunk);
-
- // Measuring from the beginning of the file.
- } else for (;;) {
- int len, offset = 0;
-
- // Error while reading does not exit. Error writing does.
- len = read(fd, toybuf, sizeof(toybuf));
- if (len<1) break;
- while (bytes > 1 || lines > 1) {
- bytes--;
- if (toybuf[offset++] == '\n') lines--;
- if (offset >= len) break;
- }
- if (offset<len) xwrite(1, toybuf+offset, len-offset);
- }
-
- // -f support: cache name/descriptor
-}
-
-void tail_main(void)
-{
- // if nothing specified, default -n to -10
- if (!(toys.optflags&(FLAG_n|FLAG_c))) TT.lines = -10;
-
- loopfiles(toys.optargs, do_tail);
-
- // do -f stuff
-}