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>
This commit is contained in:
Denys Vlasenko
parent
af0255f496
commit
40c6da433f
150
coreutils/head.c
150
coreutils/head.c
@ -21,7 +21,8 @@
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//usage: "With more than one FILE, precede each with a filename header.\n"
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//usage: "\n -n N[kbm] Print first N lines"
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//usage: IF_FEATURE_FANCY_HEAD(
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//usage: "\n -c N[kbm] Print first N bytes"
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//usage: "\n -n -N[kbm] Print all except N last lines"
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//usage: "\n -c [-]N[kbm] Print first N bytes"
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//usage: "\n -q Never print headers"
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//usage: "\n -v Always print headers"
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//usage: )
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@ -38,6 +39,110 @@
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/* This is a NOEXEC applet. Be very careful! */
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#if !ENABLE_FEATURE_FANCY_HEAD
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# define print_first_N(fp,count,bytes) print_first_N(fp,count)
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#endif
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static void
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print_first_N(FILE *fp, unsigned long count, bool count_bytes)
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{
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#if !ENABLE_FEATURE_FANCY_HEAD
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const int count_bytes = 0;
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#endif
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while (count) {
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int c = getc(fp);
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if (c == EOF)
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break;
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if (count_bytes || (c == '\n'))
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--count;
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putchar(c);
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}
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}
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#if ENABLE_FEATURE_FANCY_HEAD
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static void
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print_except_N_last_bytes(FILE *fp, unsigned count)
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{
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unsigned char *circle = xmalloc(++count);
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unsigned head = 0;
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for(;;) {
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int c;
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c = getc(fp);
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if (c == EOF)
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goto ret;
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circle[head++] = c;
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if (head == count)
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break;
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}
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for (;;) {
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int c;
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if (head == count)
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head = 0;
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putchar(circle[head]);
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c = getc(fp);
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if (c == EOF)
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goto ret;
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circle[head] = c;
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head++;
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}
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ret:
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free(circle);
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}
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static void
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print_except_N_last_lines(FILE *fp, unsigned count)
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{
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char **circle = xzalloc((++count) * sizeof(circle[0]));
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unsigned head = 0;
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for(;;) {
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char *c;
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c = xmalloc_fgets(fp);
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if (!c)
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goto ret;
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circle[head++] = c;
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if (head == count)
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break;
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}
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for (;;) {
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char *c;
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if (head == count)
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head = 0;
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fputs(circle[head], stdout);
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c = xmalloc_fgets(fp);
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if (!c)
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goto ret;
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free(circle[head]);
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circle[head++] = c;
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}
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ret:
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head = 0;
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for(;;) {
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free(circle[head++]);
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if (head == count)
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break;
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}
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free(circle);
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}
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#else
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/* Must never be called */
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void print_except_N_last_bytes(FILE *fp, unsigned count);
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void print_except_N_last_lines(FILE *fp, unsigned count);
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#endif
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#if !ENABLE_FEATURE_FANCY_HEAD
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# define eat_num(negative_N,p) eat_num(p)
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#endif
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static unsigned long
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eat_num(bool *negative_N, const char *p)
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{
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#if ENABLE_FEATURE_FANCY_HEAD
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if (*p == '-') {
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*negative_N = 1;
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p++;
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}
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#endif
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return xatoul_sfx(p, head_tail_suffixes);
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}
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static const char head_opts[] ALIGN1 =
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"n:"
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#if ENABLE_FEATURE_FANCY_HEAD
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@ -52,8 +157,13 @@ int head_main(int argc, char **argv)
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{
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unsigned long count = 10;
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#if ENABLE_FEATURE_FANCY_HEAD
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int count_bytes = 0;
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int header_threshhold = 1;
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bool count_bytes = 0;
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bool negative_N = 0;
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#else
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# define header_threshhold 1
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# define count_bytes 0
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# define negative_N 0
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#endif
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FILE *fp;
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const char *fmt;
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@ -68,7 +178,7 @@ int head_main(int argc, char **argv)
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) {
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--argc;
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++argv;
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p = (*argv) + 1;
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p = argv[0] + 1;
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goto GET_COUNT;
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}
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#endif
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@ -92,7 +202,7 @@ int head_main(int argc, char **argv)
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#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_HEAD
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GET_COUNT:
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#endif
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count = xatoul_sfx(p, head_tail_suffixes);
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count = eat_num(&negative_N, p);
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break;
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default:
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bb_show_usage();
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@ -105,39 +215,35 @@ int head_main(int argc, char **argv)
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*--argv = (char*)"-";
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fmt = header_fmt_str + 1;
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#if ENABLE_FEATURE_FANCY_HEAD
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if (argc <= header_threshhold) {
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#if ENABLE_FEATURE_FANCY_HEAD
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header_threshhold = 0;
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}
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#else
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if (argc <= 1) {
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fmt += 11; /* "" */
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}
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/* Now define some things here to avoid #ifdefs in the code below.
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* These should optimize out of the if conditions below. */
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#define header_threshhold 1
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#define count_bytes 0
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#endif
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}
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if (negative_N) {
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if (count >= INT_MAX / sizeof(char*))
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bb_error_msg("count is too big: %lu", count);
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}
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do {
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fp = fopen_or_warn_stdin(*argv);
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if (fp) {
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unsigned long i;
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if (fp == stdin) {
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*argv = (char *) bb_msg_standard_input;
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}
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if (header_threshhold) {
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printf(fmt, *argv);
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}
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i = count;
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while (i) {
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int c = getc(fp);
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if (c == EOF)
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break;
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if (count_bytes || (c == '\n'))
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--i;
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putchar(c);
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if (negative_N) {
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if (count_bytes) {
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print_except_N_last_bytes(fp, count);
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} else {
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print_except_N_last_lines(fp, count);
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}
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} else {
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print_first_N(fp, count, count_bytes);
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}
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die_if_ferror_stdout();
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if (fclose_if_not_stdin(fp)) {
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