[glibc/siddhesh/gai-cleanup2] gaih_inet: Generic allocation tracking

[glibc/siddhesh/gai-cleanup2] gaih_inet: Generic allocation tracking

[Siddhesh Poyarekar]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=1ae1143f50f5ed704d314c79b3fffb2edbe4419b

commit 1ae1143f50f5ed704d314c79b3fffb2edbe4419b
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date:   Mon Feb 28 13:43:19 2022 +0530

    gaih_inet: Generic allocation tracking
    
    Add tracking of allocations in gaih_inet so that all blocks allocated
    during lookup are freed at the end.
    
    Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

Diff:
---
 sysdeps/posix/getaddrinfo.c | 77 ++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 70 insertions(+), 7 deletions(-)

diff --git a/sysdeps/posix/getaddrinfo.c b/sysdeps/posix/getaddrinfo.c
index 28e9f9bd06..d3abc59ba9 100644
--- a/sysdeps/posix/getaddrinfo.c
+++ b/sysdeps/posix/getaddrinfo.c
@@ -116,6 +116,50 @@ struct gaih_typeproto
     char name[8];
   };
 
+struct gaih_lookup_result
+{
+  struct gaih_addrtuple *at;		/* The first result tuple.  */
+  struct scratch_buffer *allocs;	/* Pointers to allocated tuples.  */
+  size_t nallocs;			/* Count of such pointers.  */
+};
+
+/* Initialize RES with BUF, an initialized scratch buffer.  */
+
+static void
+gaih_lookup_result_init (struct gaih_lookup_result *res,
+			 struct scratch_buffer *buf)
+{
+  res->allocs = buf;
+}
+
+/* Record BUF in RES as an allocated block.  */
+
+static bool
+gaih_lookup_result_push_alloc (struct gaih_lookup_result *res, void *buf)
+{
+  size_t nallocs = res->nallocs + 1;
+  if (nallocs * sizeof (void *) > res->allocs->length
+      && !scratch_buffer_grow_preserve (res->allocs))
+    return false;
+
+  ((void **) res->allocs->data)[nallocs - 1] = buf;
+  res->nallocs = nallocs;
+  return true;
+}
+
+/* Free up resources held in RES.  */
+
+static void
+gaih_lookup_result_free (struct gaih_lookup_result *res)
+{
+  res->at = NULL;
+  size_t nallocs = res->nallocs;
+  while (nallocs-- > 0)
+    free (((void **) res->allocs->data)[nallocs]);
+
+  res->nallocs = 0;
+}
+
 /* Values for `protoflag'.  */
 #define GAI_PROTO_NOSERVICE	1
 #define GAI_PROTO_PROTOANY	2
@@ -416,9 +460,9 @@ get_servtuples (const struct gaih_service *service, const struct addrinfo *req,
 
 static int
 get_numeric_res (const char *name, const struct addrinfo *req,
-		 struct gaih_addrtuple **pat)
+		 struct gaih_lookup_result *res)
 {
-  *pat = NULL;
+  res->at = NULL;
   uint32_t addr[4] = {0};
 
   if (__inet_aton_exact (name, (struct in_addr *) addr) != 0)
@@ -454,7 +498,13 @@ get_numeric_res (const char *name, const struct addrinfo *req,
 	  at->name = canonbuf;
 	}
 
-      *pat = at;
+      if (!gaih_lookup_result_push_alloc (res, at))
+	{
+	  free (at);
+	  return -EAI_MEMORY;
+	}
+
+      res->at = at;
       return 0;
     }
 
@@ -505,7 +555,13 @@ get_numeric_res (const char *name, const struct addrinfo *req,
 	  at->name = canonbuf;
 	}
 
-      *pat = at;
+      if (!gaih_lookup_result_push_alloc (res, at))
+	{
+	  free (at);
+	  return -EAI_MEMORY;
+	}
+
+      res->at = at;
       return 0;
     }
 
@@ -540,6 +596,9 @@ gaih_inet (const char *name, const struct gaih_service *service,
   struct gaih_addrtuple *addrmem = NULL;
   char *canonbuf = NULL;
   int result = 0;
+  struct gaih_lookup_result res = {0};
+  struct scratch_buffer resbuf;
+  scratch_buffer_init (&resbuf);
 
   if (name != NULL)
     {
@@ -553,11 +612,13 @@ gaih_inet (const char *name, const struct gaih_service *service,
 	  malloc_name = true;
 	}
 
-      if ((result = get_numeric_res (name, req, &at)) != 0)
+      gaih_lookup_result_init (&res, &resbuf);
+
+      if ((result = get_numeric_res (name, req, &res)) != 0)
 	goto free_and_return;
-      else if (at != NULL)
+      else if (res.at != NULL)
 	{
-	  addrmem = at;
+	  at = res.at;
 	  canon = canonbuf = at->name;
 	  goto process_list;
 	}
@@ -1123,6 +1184,8 @@ gaih_inet (const char *name, const struct gaih_service *service,
     free ((char *) name);
   free (addrmem);
   free (canonbuf);
+  gaih_lookup_result_free (&res);
+  scratch_buffer_free (&resbuf);
 
   return result;
 }