getline: Rename &n parameter as &allocsize.

The second parameter passed into getline(3) is the size of the
allocated buffer, *NOT* the length of the returned line.  This can be
confusing, so rename this parameter as 'allocsize' consistently
throughout the code.

This is just code motion.
(cherry picked from commit e527aed895)

daemon/lvm-filter.c

@@ -155,8 +155,8 @@ set_filter (const char *filter)
   }
 
   CLEANUP_FREE char *line = NULL;
-  size_t len = 0;
-  while (getline (&line, &len, ifp) != -1) {
+  size_t allocsize = 0;
+  while (getline (&line, &allocsize, ifp) != -1) {
     int r;
     if (is_filter_line (line)) {
       r = fprintf (ofp, "    filter = [ %s ]\n", filter);

daemon/md.c

@@ -442,7 +442,7 @@ do_md_stat (const char *md)
   size_t mdlen;
   FILE *fp;
   CLEANUP_FREE char *line = NULL;
-  size_t len = 0;
+  size_t allocsize = 0;
   ssize_t n;
   guestfs_int_mdstat_list *ret = NULL;
 
@@ -457,7 +457,7 @@ do_md_stat (const char *md)
   }
 
   /* Search for a line which begins with "<md> : ". */
-  while ((n = getline (&line, &len, fp)) != -1) {
+  while ((n = getline (&line, &allocsize, fp)) != -1) {
     if (STRPREFIX (line, md) &&
         line[mdlen] == ' ' && line[mdlen+1] == ':' && line[mdlen+2] == ' ') {
       /* Found it. */

examples/libvirt_auth.c

@@ -104,7 +104,7 @@ auth_callback (guestfs_h *g,
   size_t i;
   char *prompt;
   char *reply = NULL;
-  size_t replylen;
+  size_t allocsize;
   char *pass;
   ssize_t len;
   int r;
@@ -129,7 +129,7 @@ auth_callback (guestfs_h *g,
         printf ("%s: ", prompt);
       free (prompt);
 
-      len = getline (&reply, &replylen, stdin);
+      len = getline (&reply, &allocsize, stdin);
       if (len == -1) {
         perror ("getline");
         exit (EXIT_FAILURE);

fish/fish.c

@@ -972,7 +972,7 @@ execute_and_inline (const char *cmd, int global_exit_on_error)
 {
   FILE *pp;
   CLEANUP_FREE char *line = NULL;
-  size_t len = 0;
+  size_t allocsize = 0;
   ssize_t n;
   int exit_on_error;
   struct parsed_command pcmd;
@@ -983,7 +983,7 @@ execute_and_inline (const char *cmd, int global_exit_on_error)
     return -1;
   }
 
-  while ((n = getline (&line, &len, pp)) != -1) {
+  while ((n = getline (&line, &allocsize, pp)) != -1) {
     exit_on_error = global_exit_on_error;
 
     /* Chomp final line ending which parse_command_line would not expect. */

fish/keys.c

@@ -41,7 +41,7 @@ read_key (const char *param)
   char *ret = NULL;
   int tty;
   int tcset = 0;
-  size_t n = 0;
+  size_t allocsize = 0;
   ssize_t len;
 
   /* Read and write to /dev/tty if available. */
@@ -69,7 +69,7 @@ read_key (const char *param)
     }
   }
 
-  len = getline (&ret, &n, infp);
+  len = getline (&ret, &allocsize, infp);
   if (len == -1) {
     perror ("getline");
     ret = NULL;

tests/mount-local/test-parallel-mount-local.c

@@ -466,13 +466,13 @@ read_line_from (const char *cmd)
 {
   FILE *pp;
   char *ret = NULL;
-  size_t n;
+  size_t allocsize;
 
   pp = popen (cmd, "r");
   if (pp == NULL)
     error (EXIT_FAILURE, errno, "%s: external command failed", cmd);
 
-  if (getline (&ret, &n, pp) == -1)
+  if (getline (&ret, &allocsize, pp) == -1)
     error (EXIT_FAILURE, errno, "could not read line from external command");
 
   if (pclose (pp) == -1)