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