> Therefore I think it would be good to add a "Shrink BUF before returning it."
> logic also to
> areadlink-with-size.c
> areadlinkat-with-size.c
> etc.
Done as follows:
- For areadlink-with-size, areadlinkat-with-size, xgethostname, xgetdomainname
by shrinking the result before returning it.
- In getcwd-lgpl and getcwd, shrinking is already done. But it may call
realloc (P, SIZE) when the block allocated is already of size SIZE. It
ought to be a no-op, but actually isn't on all platforms (on MSVC when
SIZE is one of 8, 16, 32, ..., 16384).
- I'm not touching getdelim.c, because the calling convention of this function
is made for calling getdelim() in a loop, and the buffer is meant to
occasionally grow, not constantly grow and shrink and grow shrink ...
>From eb76defb19b3cc01e12d77d8cc96d402b9b5097d Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Sat, 6 Jul 2019 00:39:07 +0200
Subject: [PATCH 1/5] areadlink-with-size: Don't return an excessive memory
allocation.
Reported by Andreas Dilger <adil...@whamcloud.com>.
* lib/areadlink-with-size.c (areadlink_with_size): Shrink the buffer
before returning it.
---
ChangeLog | 7 +++++++
lib/areadlink-with-size.c | 7 +++++++
2 files changed, 14 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index d6209ef..c0ee6ce 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2019-07-05 Bruno Haible <br...@clisp.org>
+
+ areadlink-with-size: Don't return an excessive memory allocation.
+ Reported by Andreas Dilger <adil...@whamcloud.com>.
+ * lib/areadlink-with-size.c (areadlink_with_size): Shrink the buffer
+ before returning it.
+
2019-07-03 Bruno Haible <br...@clisp.org>
renameatu: Fix test failure on MSVC.
diff --git a/lib/areadlink-with-size.c b/lib/areadlink-with-size.c
index eacad3f..364cc08 100644
--- a/lib/areadlink-with-size.c
+++ b/lib/areadlink-with-size.c
@@ -87,6 +87,13 @@ areadlink_with_size (char const *file, size_t size)
if (link_length < buf_size)
{
buffer[link_length] = 0;
+ /* Shrink BUFFER before returning it. */
+ if (link_length + 1 < buf_size)
+ {
+ char *shrinked_buffer = realloc (buffer, link_length + 1);
+ if (shrinked_buffer != NULL)
+ buffer = shrinked_buffer;
+ }
return buffer;
}
--
2.7.4
>From 8f91b5cf3514d664289afaace0d6f832b9608f20 Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Sat, 6 Jul 2019 00:40:34 +0200
Subject: [PATCH 2/5] areadlinkat-with-size: Don't return an excessive memory
allocation.
* lib/areadlinkat-with-size.c (areadlinkat_with_size): Shrink the buffer
before returning it.
---
ChangeLog | 6 ++++++
lib/areadlinkat-with-size.c | 7 +++++++
2 files changed, 13 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index c0ee6ce..d091eb1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
2019-07-05 Bruno Haible <br...@clisp.org>
+ areadlinkat-with-size: Don't return an excessive memory allocation.
+ * lib/areadlinkat-with-size.c (areadlinkat_with_size): Shrink the buffer
+ before returning it.
+
+2019-07-05 Bruno Haible <br...@clisp.org>
+
areadlink-with-size: Don't return an excessive memory allocation.
Reported by Andreas Dilger <adil...@whamcloud.com>.
* lib/areadlink-with-size.c (areadlink_with_size): Shrink the buffer
diff --git a/lib/areadlinkat-with-size.c b/lib/areadlinkat-with-size.c
index ed00b98..5b2bccc 100644
--- a/lib/areadlinkat-with-size.c
+++ b/lib/areadlinkat-with-size.c
@@ -92,6 +92,13 @@ areadlinkat_with_size (int fd, char const *file, size_t size)
if (link_length < buf_size)
{
buffer[link_length] = 0;
+ /* Shrink BUFFER before returning it. */
+ if (link_length + 1 < buf_size)
+ {
+ char *shrinked_buffer = realloc (buffer, link_length + 1);
+ if (shrinked_buffer != NULL)
+ buffer = shrinked_buffer;
+ }
return buffer;
}
--
2.7.4
>From 98802d166215602a88988ae566259edf4f67efe8 Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Sat, 6 Jul 2019 00:43:01 +0200
Subject: [PATCH 3/5] xgethostname: Don't return an excessive memory
allocation.
* lib/xgethostname.c (xgethostname): Shrink the hostname buffer before
returning it.
---
ChangeLog | 6 ++++++
lib/xgethostname.c | 11 +++++++++++
2 files changed, 17 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index d091eb1..c8dd18a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
2019-07-05 Bruno Haible <br...@clisp.org>
+ xgethostname: Don't return an excessive memory allocation.
+ * lib/xgethostname.c (xgethostname): Shrink the hostname buffer before
+ returning it.
+
+2019-07-05 Bruno Haible <br...@clisp.org>
+
areadlinkat-with-size: Don't return an excessive memory allocation.
* lib/areadlinkat-with-size.c (areadlinkat_with_size): Shrink the buffer
before returning it.
diff --git a/lib/xgethostname.c b/lib/xgethostname.c
index eba34b8..4bcb00f 100644
--- a/lib/xgethostname.c
+++ b/lib/xgethostname.c
@@ -70,5 +70,16 @@ xgethostname (void)
}
}
+ /* Shrink HOSTNAME before returning it. */
+ {
+ size_t actual_size = strlen (hostname) + 1;
+ if (actual_size < size)
+ {
+ char *shrinked_hostname = realloc (hostname, actual_size);
+ if (shrinked_hostname != NULL)
+ hostname = shrinked_hostname;
+ }
+ }
+
return hostname;
}
--
2.7.4
>From ac7390ac0884d155d3adc9d0f992413adcaaff87 Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Sat, 6 Jul 2019 00:43:59 +0200
Subject: [PATCH 4/5] xgetdomainname: Don't return an excessive memory
allocation.
* lib/xgetdomainname.c (xgetdomainname): Shrink the domainname buffer
before returning it.
---
ChangeLog | 6 ++++++
lib/xgetdomainname.c | 11 +++++++++++
2 files changed, 17 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index c8dd18a..1f5f18b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
2019-07-05 Bruno Haible <br...@clisp.org>
+ xgetdomainname: Don't return an excessive memory allocation.
+ * lib/xgetdomainname.c (xgetdomainname): Shrink the domainname buffer
+ before returning it.
+
+2019-07-05 Bruno Haible <br...@clisp.org>
+
xgethostname: Don't return an excessive memory allocation.
* lib/xgethostname.c (xgethostname): Shrink the hostname buffer before
returning it.
diff --git a/lib/xgetdomainname.c b/lib/xgetdomainname.c
index 2f59008..65df990 100644
--- a/lib/xgetdomainname.c
+++ b/lib/xgetdomainname.c
@@ -73,5 +73,16 @@ xgetdomainname (void)
domainname = xrealloc (domainname, size);
}
+ /* Shrink DOMAINNAME before returning it. */
+ {
+ size_t actual_size = strlen (domainname) + 1;
+ if (actual_size < size)
+ {
+ char *shrinked_domainname = realloc (domainname, actual_size);
+ if (shrinked_domainname != NULL)
+ domainname = shrinked_domainname;
+ }
+ }
+
return domainname;
}
--
2.7.4
>From d44241344e8455c59ea04440706cfaf72862c404 Mon Sep 17 00:00:00 2001
From: Bruno Haible <br...@clisp.org>
Date: Sat, 6 Jul 2019 00:47:12 +0200
Subject: [PATCH 5/5] getcwd-lgpl, getcwd: Don't call realloc when it is
pointless.
* lib/getcwd-lgpl.c (rpl_getcwd): Don't call realloc if the result's
needed size is equal to the allocated size.
* lib/getcwd.c (__getcwd): Likewise.
---
ChangeLog | 7 +++++++
lib/getcwd-lgpl.c | 13 +++++++++----
lib/getcwd.c | 2 +-
3 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 1f5f18b..98d5531 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
2019-07-05 Bruno Haible <br...@clisp.org>
+ getcwd-lgpl, getcwd: Don't call realloc when it is pointless.
+ * lib/getcwd-lgpl.c (rpl_getcwd): Don't call realloc if the result's
+ needed size is equal to the allocated size.
+ * lib/getcwd.c (__getcwd): Likewise.
+
+2019-07-05 Bruno Haible <br...@clisp.org>
+
xgetdomainname: Don't return an excessive memory allocation.
* lib/xgetdomainname.c (xgetdomainname): Shrink the domainname buffer
before returning it.
diff --git a/lib/getcwd-lgpl.c b/lib/getcwd-lgpl.c
index b224cfc..1eaac78 100644
--- a/lib/getcwd-lgpl.c
+++ b/lib/getcwd-lgpl.c
@@ -115,10 +115,15 @@ rpl_getcwd (char *buf, size_t size)
}
else
{
- /* Trim to fit, if possible. */
- result = realloc (buf, strlen (buf) + 1);
- if (!result)
- result = buf;
+ /* Here result == buf. */
+ /* Shrink result before returning it. */
+ size_t actual_size = strlen (result) + 1;
+ if (actual_size < size)
+ {
+ char *shrinked_result = realloc (result, actual_size);
+ if (shrinked_result != NULL)
+ result = shrinked_result;
+ }
}
return result;
}
diff --git a/lib/getcwd.c b/lib/getcwd.c
index 8f15f56..bf87809 100644
--- a/lib/getcwd.c
+++ b/lib/getcwd.c
@@ -443,7 +443,7 @@ __getcwd (char *buf, size_t size)
if (size == 0)
/* Ensure that the buffer is only as large as necessary. */
- buf = realloc (dir, used);
+ buf = (used < allocated ? realloc (dir, used) : dir);
if (buf == NULL)
/* Either buf was NULL all along, or 'realloc' failed but
--
2.7.4
