libbb: introduce and use xrealloc_vector

function                                             old     new   delta
xrealloc_vector_helper                                 -      51     +51
create_list                                           84      99     +15
getopt_main                                          690     695      +5
passwd_main                                         1049    1053      +4
get_cached                                            85      89      +4
msh_main                                            1377    1380      +3
add_match                                             42      41      -1
read_lines                                           720     718      -2
grave                                               1068    1066      -2
fill_match_lines                                     143     141      -2
add_to_dirlist                                        67      65      -2
add_input_file                                        49      47      -2
act                                                  252     250      -2
fsck_main                                           2252    2246      -6
man_main                                             765     757      -8
bb_internal_initgroups                               228     220      -8
cut_main                                            1052    1041     -11
add_edge_to_node                                      55      43     -12
dpkg_main                                           3851    3835     -16
ifupdown_main                                       2202    2178     -24
sort_main                                            838     812     -26
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 5/15 up/down: 82/-124)          Total: -42 bytes

7 files changed, 65 insertions, 18 deletions

diff --git a/libbb/Kbuild b/libbb/Kbuild
index 5cbecd537..c49297b12 100644
--- a/libbb/Kbuild
+++ b/libbb/Kbuild
@@ -109,6 +109,7 @@ lib-y += xfunc_die.o
 lib-y += xgetcwd.o
 lib-y += xgethostbyname.o
 lib-y += xreadlink.o
+lib-y += xrealloc_vector.o
 
 # conditionally compiled objects:
 lib-$(CONFIG_FEATURE_MOUNT_LOOP) += loop.o
diff --git a/libbb/dump.c b/libbb/dump.c
index c45595285..8a90aac5a 100644
--- a/libbb/dump.c
+++ b/libbb/dump.c
@@ -245,7 +245,7 @@ static void rewrite(FS * fs)
 			{
 				savech = *p3;
 				*p3 = '\0';
-				pr->fmt = xrealloc(pr->fmt, strlen(pr->fmt)+(p3-p2)+1);
+				pr->fmt = xrealloc(pr->fmt, strlen(pr->fmt) + (p3-p2) + 1);
 				strcat(pr->fmt, p2);
 				*p3 = savech;
 				p2 = p3;
diff --git a/libbb/get_line_from_file.c b/libbb/get_line_from_file.c
index 66ea5a1a5..3a76f49a0 100644
--- a/libbb/get_line_from_file.c
+++ b/libbb/get_line_from_file.c
@@ -42,7 +42,7 @@ char* FAST_FUNC bb_get_chunk_from_file(FILE *file, int *end)
 		//	free(linebuf);
 		//	return NULL;
 		//}
-		linebuf = xrealloc(linebuf, idx+1);
+		linebuf = xrealloc(linebuf, idx + 1);
 		linebuf[idx] = '\0';
 	}
 	return linebuf;
diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index 3ef47ba71..a46b5d2c4 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -400,11 +400,8 @@ static void free_tab_completion_data(void)
 
 static void add_match(char *matched)
 {
-	int nm = num_matches;
-	int nm1 = nm + 1;
-
-	matches = xrealloc(matches, nm1 * sizeof(char *));
-	matches[nm] = matched;
+	matches = xrealloc_vector(matches, 4, num_matches);
+	matches[num_matches] = matched;
 	num_matches++;
 }
 
diff --git a/libbb/mtab.c b/libbb/mtab.c
index 57654a695..2c171322a 100644
--- a/libbb/mtab.c
+++ b/libbb/mtab.c
@@ -27,14 +27,14 @@ void FAST_FUNC erase_mtab(const char *name)
 	}
 
 	while ((m = getmntent(mountTable)) != 0) {
+		entries = xrealloc(entries, 3, count);
+		entries[count].mnt_fsname = xstrdup(m->mnt_fsname);
+		entries[count].mnt_dir = xstrdup(m->mnt_dir);
+		entries[count].mnt_type = xstrdup(m->mnt_type);
+		entries[count].mnt_opts = xstrdup(m->mnt_opts);
+		entries[count].mnt_freq = m->mnt_freq;
+		entries[count].mnt_passno = m->mnt_passno;
 		i = count++;
-		entries = xrealloc(entries, count * sizeof(entries[0]));
-		entries[i].mnt_fsname = xstrdup(m->mnt_fsname);
-		entries[i].mnt_dir = xstrdup(m->mnt_dir);
-		entries[i].mnt_type = xstrdup(m->mnt_type);
-		entries[i].mnt_opts = xstrdup(m->mnt_opts);
-		entries[i].mnt_freq = m->mnt_freq;
-		entries[i].mnt_passno = m->mnt_passno;
 	}
 	endmntent(mountTable);
 
diff --git a/libbb/procps.c b/libbb/procps.c
index 7d49d83ce..a5168a077 100644
--- a/libbb/procps.c
+++ b/libbb/procps.c
@@ -45,8 +45,8 @@ static int get_cached(cache_t *cp, unsigned id)
 	for (i = 0; i < cp->size; i++)
 		if (cp->cache[i].id == id)
 			return i;
-	i = cp->size++;
-	cp->cache = xrealloc(cp->cache, cp->size * sizeof(*cp->cache));
+	i = cp->size;
+	cp->cache = xrealloc_vector(cp->cache, 2, cp->size++);
 	cp->cache[i++].id = id;
 	return -i;
 }
@@ -59,8 +59,8 @@ static char* get_cached(cache_t *cp, unsigned id, ug_func* fp)
 	for (i = 0; i < cp->size; i++)
 		if (cp->cache[i].id == id)
 			return cp->cache[i].name;
-	i = cp->size++;
-	cp->cache = xrealloc(cp->cache, cp->size * sizeof(*cp->cache));
+	i = cp->size;
+	cp->cache = xrealloc_vector(cp->cache, 2, cp->size++);
 	cp->cache[i].id = id;
 	/* Never fails. Generates numeric string if name isn't found */
 	fp(cp->cache[i].name, sizeof(cp->cache[i].name), id);
diff --git a/libbb/read.c b/libbb/read.c
index 7b804125a..405e216dc 100644
--- a/libbb/read.c
+++ b/libbb/read.c
@@ -291,3 +291,52 @@ void* FAST_FUNC xmalloc_xopen_read_close(const char *filename, size_t *sizep)
 		bb_perror_msg_and_die("can't read '%s'", filename);
 	return buf;
 }
+
+/* libbb candidate */
+#if 0
+static void *xmalloc_read(int fd, size_t *sizep)
+{
+	char *buf;
+	size_t size, rd_size, total;
+	off_t to_read;
+	struct stat st;
+
+	to_read = sizep ? *sizep : INT_MAX; /* max to read */
+
+	/* Estimate file size */
+	st.st_size = 0; /* in case fstat fails, assume 0 */
+	fstat(fd, &st);
+	/* /proc/N/stat files report st_size 0 */
+	/* In order to make such files readable, we add small const */
+	size = (st.st_size | 0x3ff) + 1;
+
+	total = 0;
+	buf = NULL;
+	while (1) {
+		if (to_read < size)
+			size = to_read;
+		buf = xrealloc(buf, total + size + 1);
+		rd_size = full_read(fd, buf + total, size);
+		if ((ssize_t)rd_size < 0) { /* error */
+			free(buf);
+			return NULL;
+		}
+		total += rd_size;
+		if (rd_size < size) /* EOF */
+			break;
+		to_read -= rd_size;
+		if (to_read <= 0)
+			break;
+		/* grow by 1/8, but in [1k..64k] bounds */
+		size = ((total / 8) | 0x3ff) + 1;
+		if (size > 64*1024)
+			size = 64*1024;
+	}
+	xrealloc(buf, total + 1);
+	buf[total] = '\0';
+
+	if (sizep)
+		*sizep = total;
+	return buf;
+}
+#endif