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authorDenys Vlasenko <vda.linux@googlemail.com>2013-02-25 00:26:09 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2013-02-25 00:26:09 (GMT)
commit40c6da433f0900d451e46da86422d89f3878d40c (patch)
tree7e659456dff909d00371f4393b79f0bcd0b18c69
parentaf0255f49681bcc78830a56af885e891eca210f4 (diff)
downloadbusybox-40c6da433f0900d451e46da86422d89f3878d40c.tar.gz
busybox-40c6da433f0900d451e46da86422d89f3878d40c.tar.bz2
head: support -n -NUM and -c -NUM
function old new delta head_main 406 832 +426 packed_usage 29234 29252 +18 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 2/0 up/down: 444/0) Total: 444 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--coreutils/head.c150
1 files changed, 128 insertions, 22 deletions
diff --git a/coreutils/head.c b/coreutils/head.c
index 598fccb..291e1ce 100644
--- a/coreutils/head.c
+++ b/coreutils/head.c
@@ -21,7 +21,8 @@
//usage: "With more than one FILE, precede each with a filename header.\n"
//usage: "\n -n N[kbm] Print first N lines"
//usage: IF_FEATURE_FANCY_HEAD(
-//usage: "\n -c N[kbm] Print first N bytes"
+//usage: "\n -n -N[kbm] Print all except N last lines"
+//usage: "\n -c [-]N[kbm] Print first N bytes"
//usage: "\n -q Never print headers"
//usage: "\n -v Always print headers"
//usage: )
@@ -38,6 +39,110 @@
/* This is a NOEXEC applet. Be very careful! */
+#if !ENABLE_FEATURE_FANCY_HEAD
+# define print_first_N(fp,count,bytes) print_first_N(fp,count)
+#endif
+static void
+print_first_N(FILE *fp, unsigned long count, bool count_bytes)
+{
+#if !ENABLE_FEATURE_FANCY_HEAD
+ const int count_bytes = 0;
+#endif
+ while (count) {
+ int c = getc(fp);
+ if (c == EOF)
+ break;
+ if (count_bytes || (c == '\n'))
+ --count;
+ putchar(c);
+ }
+}
+
+#if ENABLE_FEATURE_FANCY_HEAD
+static void
+print_except_N_last_bytes(FILE *fp, unsigned count)
+{
+ unsigned char *circle = xmalloc(++count);
+ unsigned head = 0;
+ for(;;) {
+ int c;
+ c = getc(fp);
+ if (c == EOF)
+ goto ret;
+ circle[head++] = c;
+ if (head == count)
+ break;
+ }
+ for (;;) {
+ int c;
+ if (head == count)
+ head = 0;
+ putchar(circle[head]);
+ c = getc(fp);
+ if (c == EOF)
+ goto ret;
+ circle[head] = c;
+ head++;
+ }
+ ret:
+ free(circle);
+}
+
+static void
+print_except_N_last_lines(FILE *fp, unsigned count)
+{
+ char **circle = xzalloc((++count) * sizeof(circle[0]));
+ unsigned head = 0;
+ for(;;) {
+ char *c;
+ c = xmalloc_fgets(fp);
+ if (!c)
+ goto ret;
+ circle[head++] = c;
+ if (head == count)
+ break;
+ }
+ for (;;) {
+ char *c;
+ if (head == count)
+ head = 0;
+ fputs(circle[head], stdout);
+ c = xmalloc_fgets(fp);
+ if (!c)
+ goto ret;
+ free(circle[head]);
+ circle[head++] = c;
+ }
+ ret:
+ head = 0;
+ for(;;) {
+ free(circle[head++]);
+ if (head == count)
+ break;
+ }
+ free(circle);
+}
+#else
+/* Must never be called */
+void print_except_N_last_bytes(FILE *fp, unsigned count);
+void print_except_N_last_lines(FILE *fp, unsigned count);
+#endif
+
+#if !ENABLE_FEATURE_FANCY_HEAD
+# define eat_num(negative_N,p) eat_num(p)
+#endif
+static unsigned long
+eat_num(bool *negative_N, const char *p)
+{
+#if ENABLE_FEATURE_FANCY_HEAD
+ if (*p == '-') {
+ *negative_N = 1;
+ p++;
+ }
+#endif
+ return xatoul_sfx(p, head_tail_suffixes);
+}
+
static const char head_opts[] ALIGN1 =
"n:"
#if ENABLE_FEATURE_FANCY_HEAD
@@ -52,8 +157,13 @@ int head_main(int argc, char **argv)
{
unsigned long count = 10;
#if ENABLE_FEATURE_FANCY_HEAD
- int count_bytes = 0;
int header_threshhold = 1;
+ bool count_bytes = 0;
+ bool negative_N = 0;
+#else
+# define header_threshhold 1
+# define count_bytes 0
+# define negative_N 0
#endif
FILE *fp;
const char *fmt;
@@ -68,7 +178,7 @@ int head_main(int argc, char **argv)
) {
--argc;
++argv;
- p = (*argv) + 1;
+ p = argv[0] + 1;
goto GET_COUNT;
}
#endif
@@ -92,7 +202,7 @@ int head_main(int argc, char **argv)
#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
GET_COUNT:
#endif
- count = xatoul_sfx(p, head_tail_suffixes);
+ count = eat_num(&negative_N, p);
break;
default:
bb_show_usage();
@@ -105,39 +215,35 @@ int head_main(int argc, char **argv)
*--argv = (char*)"-";
fmt = header_fmt_str + 1;
-#if ENABLE_FEATURE_FANCY_HEAD
if (argc <= header_threshhold) {
+#if ENABLE_FEATURE_FANCY_HEAD
header_threshhold = 0;
- }
#else
- if (argc <= 1) {
fmt += 11; /* "" */
- }
- /* Now define some things here to avoid #ifdefs in the code below.
- * These should optimize out of the if conditions below. */
-#define header_threshhold 1
-#define count_bytes 0
#endif
+ }
+ if (negative_N) {
+ if (count >= INT_MAX / sizeof(char*))
+ bb_error_msg("count is too big: %lu", count);
+ }
do {
fp = fopen_or_warn_stdin(*argv);
if (fp) {
- unsigned long i;
-
if (fp == stdin) {
*argv = (char *) bb_msg_standard_input;
}
if (header_threshhold) {
printf(fmt, *argv);
}
- i = count;
- while (i) {
- int c = getc(fp);
- if (c == EOF)
- break;
- if (count_bytes || (c == '\n'))
- --i;
- putchar(c);
+ if (negative_N) {
+ if (count_bytes) {
+ print_except_N_last_bytes(fp, count);
+ } else {
+ print_except_N_last_lines(fp, count);
+ }
+ } else {
+ print_first_N(fp, count, count_bytes);
}
die_if_ferror_stdout();
if (fclose_if_not_stdin(fp)) {