head,tail: use common suffix struct. simplify help text.

function                                             old     new   delta
head_tail_suffixes                                     -      32     +32
head_main                                            415     406      -9
packed_usage                                       29252   29234     -18
tail_suffixes                                         32       -     -32
head_suffixes                                         32       -     -32
------------------------------------------------------------------------------
(add/remove: 2/2 grow/shrink: 0/2 up/down: 32/-91)            Total: -59 bytes
   text    data     bss     dec     hex filename
 890474     497    7584  898555   db5fb busybox_old
 890415     497    7584  898496   db5c0 busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

5 files changed, 40 insertions, 27 deletions

diff --git a/coreutils/Kbuild.src b/coreutils/Kbuild.src
index b715b9c47..ec4ef7df2 100644
--- a/coreutils/Kbuild.src
+++ b/coreutils/Kbuild.src
@@ -35,7 +35,6 @@ lib-$(CONFIG_EXPAND)    += expand.o
 lib-$(CONFIG_FALSE)     += false.o
 lib-$(CONFIG_FOLD)      += fold.o
 lib-$(CONFIG_FSYNC)     += fsync.o
-lib-$(CONFIG_HEAD)      += head.o
 lib-$(CONFIG_INSTALL)   += install.o
 #lib-$(CONFIG_LENGTH)    += length.o
 lib-$(CONFIG_LN)        += ln.o
@@ -71,7 +70,6 @@ lib-$(CONFIG_STTY)      += stty.o
 lib-$(CONFIG_SUM)       += sum.o
 lib-$(CONFIG_SYNC)      += sync.o
 lib-$(CONFIG_TAC)       += tac.o
-lib-$(CONFIG_TAIL)      += tail.o
 lib-$(CONFIG_TEE)       += tee.o
 lib-$(CONFIG_TRUE)      += true.o
 lib-$(CONFIG_TTY)       += tty.o
diff --git a/coreutils/head.c b/coreutils/head.c
index ec4512765..598fccb64 100644
--- a/coreutils/head.c
+++ b/coreutils/head.c
@@ -11,6 +11,9 @@
 /* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */
 /* http://www.opengroup.org/onlinepubs/007904975/utilities/head.html */
 
+//kbuild:lib-$(CONFIG_HEAD) += head.o
+//kbuild:lib-$(CONFIG_HEAD) += head_tail.o
+
 //usage:#define head_trivial_usage
 //usage:       "[OPTIONS] [FILE]..."
 //usage:#define head_full_usage "\n\n"
@@ -31,6 +34,7 @@
 //usage:       "daemon:x:1:1:daemon:/usr/sbin:/bin/sh\n"
 
 #include "libbb.h"
+#include "head_tail.h"
 
 /* This is a NOEXEC applet. Be very careful! */
 
@@ -41,20 +45,12 @@ static const char head_opts[] ALIGN1 =
 #endif
         ;
 
-static const struct suffix_mult head_suffixes[] = {
-        { "b", 512 },
-        { "k", 1024 },
-        { "m", 1024*1024 },
-        { "", 0 }
-};
-
 #define header_fmt_str "\n==> %s <==\n"
 
 int head_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int head_main(int argc, char **argv)
 {
         unsigned long count = 10;
-        unsigned long i;
 #if ENABLE_FEATURE_FANCY_HEAD
         int count_bytes = 0;
         int header_threshhold = 1;
@@ -63,7 +59,6 @@ int head_main(int argc, char **argv)
         const char *fmt;
         char *p;
         int opt;
-        int c;
         int retval = EXIT_SUCCESS;
 
 #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
@@ -97,7 +92,7 @@ int head_main(int argc, char **argv)
 #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
  GET_COUNT:
 #endif
-                        count = xatoul_sfx(p, head_suffixes);
+                        count = xatoul_sfx(p, head_tail_suffixes);
                         break;
                 default:
                         bb_show_usage();
@@ -127,6 +122,8 @@ int head_main(int argc, char **argv)
         do {
                 fp = fopen_or_warn_stdin(*argv);
                 if (fp) {
+                        unsigned long i;
+
                         if (fp == stdin) {
                                 *argv = (char *) bb_msg_standard_input;
                         }
@@ -134,17 +131,19 @@ int head_main(int argc, char **argv)
                                 printf(fmt, *argv);
                         }
                         i = count;
-                        while (i && ((c = getc(fp)) != EOF)) {
-                                if (count_bytes || (c == '\n')) {
+                        while (i) {
+                                int c = getc(fp);
+                                if (c == EOF)
+                                        break;
+                                if (count_bytes || (c == '\n'))
                                         --i;
-                                }
                                 putchar(c);
                         }
+                        die_if_ferror_stdout();
                         if (fclose_if_not_stdin(fp)) {
                                 bb_simple_perror_msg(*argv);
                                 retval = EXIT_FAILURE;
                         }
-                        die_if_ferror_stdout();
                 } else {
                         retval = EXIT_FAILURE;
                 }
diff --git a/coreutils/head_tail.c b/coreutils/head_tail.c
new file mode 100644
index 000000000..1658c0d1b
--- /dev/null
+++ b/coreutils/head_tail.c
@@ -0,0 +1,14 @@
+/*
+ * Copyright (C) 2013 Denys Vlasenko
+ *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
+ */
+#include "libbb.h"
+#include "head_tail.h"
+
+const struct suffix_mult head_tail_suffixes[] = {
+        { "b", 512 },
+        { "k", 1024 },
+        { "m", 1024*1024 },
+        { "", 0 }
+};
diff --git a/coreutils/head_tail.h b/coreutils/head_tail.h
new file mode 100644
index 000000000..df19e41e0
--- /dev/null
+++ b/coreutils/head_tail.h
@@ -0,0 +1,6 @@
+/*
+ * Copyright (C) 2013 Denys Vlasenko
+ *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
+ */
+extern const struct suffix_mult head_tail_suffixes[];
diff --git a/coreutils/tail.c b/coreutils/tail.c
index b376ec863..87251da83 100644
--- a/coreutils/tail.c
+++ b/coreutils/tail.c
@@ -24,6 +24,9 @@
  * 7) lseek attempted when count==0 even if arg was +0 (from top)
  */
 
+//kbuild:lib-$(CONFIG_TAIL) += tail.o
+//kbuild:lib-$(CONFIG_TAIL) += head_tail.o
+
 //usage:#define tail_trivial_usage
 //usage:       "[OPTIONS] [FILE]..."
 //usage:#define tail_full_usage "\n\n"
@@ -34,14 +37,13 @@
 //usage:     "\n        -s SECONDS      Wait SECONDS between reads with -f"
 //usage:        )
 //usage:     "\n        -n N[kbm]       Print last N lines"
+//usage:     "\n        -n +N[kbm]      Skip N lines and print the rest"
 //usage:        IF_FEATURE_FANCY_TAIL(
-//usage:     "\n        -c N[kbm]       Print last N bytes"
+//usage:     "\n        -c [+]N[kbm]    Print last N bytes"
 //usage:     "\n        -q              Never print headers"
 //usage:     "\n        -v              Always print headers"
 //usage:     "\n"
 //usage:     "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)."
-//usage:     "\nIf N starts with a '+', output begins with the Nth item from the start"
-//usage:     "\nof each file, not from the end."
 //usage:        )
 //usage:
 //usage:#define tail_example_usage
@@ -49,13 +51,7 @@
 //usage:       "nameserver 10.0.0.1\n"
 
 #include "libbb.h"
-
-static const struct suffix_mult tail_suffixes[] = {
-        { "b", 512 },
-        { "k", 1024 },
-        { "m", 1024*1024 },
-        { "", 0 }
-};
+#include "head_tail.h"
 
 struct globals {
         bool from_top;
@@ -102,7 +98,7 @@ static unsigned eat_num(const char *p)
                 p++;
                 G.from_top = 1;
         }
-        return xatou_sfx(p, tail_suffixes);
+        return xatou_sfx(p, head_tail_suffixes);
 }
 
 int tail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;