diff options
| -rw-r--r-- | src/head.c | 28 | ||||
| -rwxr-xr-x | tests/misc/head-c.sh | 9 |
2 files changed, 29 insertions, 8 deletions
diff --git a/src/head.c b/src/head.c index d79d5f7de..00e1be17c 100644 --- a/src/head.c +++ b/src/head.c @@ -196,7 +196,7 @@ copy_fd (int src_fd, FILE *o_stream, uintmax_t n_bytes) return COPY_FD_OK; } -/* Print all but the last N_ELIDE lines from the input available via +/* Print all but the last N_ELIDE bytes from the input available via the non-seekable file descriptor FD. Return true upon success. Give a diagnostic and return false upon error. */ static bool @@ -313,18 +313,34 @@ elide_tail_bytes_pipe (const char *filename, int fd, uintmax_t n_elide_0) size_t n_read; bool buffered_enough; size_t i, i_next; - char **b; + char **b = NULL; /* Round n_elide up to a multiple of READ_BUFSIZE. */ size_t rem = READ_BUFSIZE - (n_elide % READ_BUFSIZE); size_t n_elide_round = n_elide + rem; size_t n_bufs = n_elide_round / READ_BUFSIZE + 1; - b = xcalloc (n_bufs, sizeof *b); + size_t n_alloc = 0; + size_t n_array_alloc = 0; buffered_enough = false; for (i = 0, i_next = 1; !eof; i = i_next, i_next = (i_next + 1) % n_bufs) { - if (b[i] == NULL) - b[i] = xmalloc (READ_BUFSIZE); + if (n_array_alloc == i) + { + /* reallocate between 16 and n_bufs entries. */ + if (n_array_alloc == 0) + n_array_alloc = MIN (n_bufs, 16); + else if (n_array_alloc <= n_bufs / 2) + n_array_alloc *= 2; + else + n_array_alloc = n_bufs; + b = xnrealloc (b, n_array_alloc, sizeof *b); + } + + if (! buffered_enough) + { + b[i] = xmalloc (READ_BUFSIZE); + n_alloc = i + 1; + } n_read = full_read (fd, b[i], READ_BUFSIZE); if (n_read < READ_BUFSIZE) { @@ -388,7 +404,7 @@ elide_tail_bytes_pipe (const char *filename, int fd, uintmax_t n_elide_0) } free_mem: - for (i = 0; i < n_bufs; i++) + for (i = 0; i < n_alloc; i++) free (b[i]); free (b); diff --git a/tests/misc/head-c.sh b/tests/misc/head-c.sh index 6807c4d5a..eada8d550 100755 --- a/tests/misc/head-c.sh +++ b/tests/misc/head-c.sh @@ -1,5 +1,5 @@ #!/bin/sh -# exercise the fix of 2001-08-18, based on test case from Ian Bruce +# exercise head -c # Copyright (C) 2001-2013 Free Software Foundation, Inc. @@ -19,12 +19,17 @@ . "${srcdir=.}/tests/init.sh"; path_prepend_ ./src print_ver_ head +# exercise the fix of 2001-08-18, based on test case from Ian Bruce echo abc > in || framework_failure_ - (head -c1; head -c1) < in > out || fail=1 case "$(cat out)" in ab) ;; *) fail=1 ;; esac +# Only allocate memory as needed. +# Coreutils <= 8.21 would allocate memory up front +# based on the value passed to -c +(ulimit -v 20000; head --bytes=-E < /dev/null) || fail=1 + Exit $fail |