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40c6da433

Denys Vlasenko

2013-02-25

SUCCESS Duration: 198s

Subject

head: support -n -NUM and -c -NUM

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

coreutils/head.c +128 -22

coreutils/head.c+128 -22

@@ -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)) {