pg.ddx.io pgsql-hackers@postgresql.org mailing list archive help / color / mirror / Atom feed From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>
Cc: Pg Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: adding strndup
Date: Wed, 4 Dec 2019 19:01:46 -0300
Message-ID: <20191204220146.GA28850@alvherre.pgsql> (raw )
In-Reply-To: <20191204190501.GA29287@alvherre.pgsql >
On 2019-Dec-04, Alvaro Herrera wrote:
> On 2019-Dec-04, Tom Lane wrote:
>
> > Andres Freund <andres@anarazel.de> writes:
> > > On 2019-12-04 11:40:21 -0300, Alvaro Herrera wrote:
> > >> I think this should be pretty uncontroversial, but wanted to give a
> > >> heads-up outside that thread. I attach the patch here for completeness.
> >
> > > I'd just provide pnstrdup() in the frontend, without adding strndup().
> >
> > +1 --- seems like a bunch more mechanism than is warranted. Let's
> > just open-code it in pnstrdup. We can rely on strnlen, since that's
> > already supported, and there's not much more there beyond that.
>
> I can get behind that ... it makes the patch a lot smaller.
Here it is.
I noticed that ECPG's copy was setting errno. I had forgot to do that
in my previous patch, but on second look, malloc failure already sets
it, so doing it again is pointless.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
Attachments:
v4-0001-Offer-pnstrdup-to-frontend-code.patch (text/x-diff, 5.0K) download
From c4dc0fd76e86bf97cb612bafe30847c47b77813e Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: Wed, 4 Dec 2019 11:02:34 -0300
Subject: [PATCH v4] Offer pnstrdup to frontend code
We already had it on the backend. Frontend can also use it now.
Discussion: https://postgr.es/m/20191204144021.GA17976@alvherre.pgsql
---
src/bin/pg_waldump/pg_waldump.c | 3 +--
src/bin/psql/prompt.c | 16 +++++---------
src/bin/scripts/common.c | 3 +--
src/common/fe_memutils.c | 27 ++++++++++++++++++++++++
src/include/common/fe_memutils.h | 1 +
src/interfaces/ecpg/compatlib/informix.c | 21 +-----------------
6 files changed, 36 insertions(+), 35 deletions(-)
diff --git a/src/bin/pg_waldump/pg_waldump.c b/src/bin/pg_waldump/pg_waldump.c
index 30a5851d87..a05fbe6938 100644
--- a/src/bin/pg_waldump/pg_waldump.c
+++ b/src/bin/pg_waldump/pg_waldump.c
@@ -114,8 +114,7 @@ split_path(const char *path, char **dir, char **fname)
/* directory path */
if (sep != NULL)
{
- *dir = pg_strdup(path);
- (*dir)[(sep - path) + 1] = '\0'; /* no strndup */
+ *dir = pnstrdup(path, sep - path);
*fname = pg_strdup(sep + 1);
}
/* local directory */
diff --git a/src/bin/psql/prompt.c b/src/bin/psql/prompt.c
index 41c6f21ecf..1199181521 100644
--- a/src/bin/psql/prompt.c
+++ b/src/bin/psql/prompt.c
@@ -270,13 +270,10 @@ get_prompt(promptStatus_t status, ConditionalStack cstack)
/* execute command */
case '`':
{
- FILE *fd;
- char *file = pg_strdup(p + 1);
- int cmdend;
+ int cmdend = strcspn(p + 1, "`");
+ char *file = pnstrdup(p + 1, cmdend);
+ FILE *fd = popen(file, "r");
- cmdend = strcspn(file, "`");
- file[cmdend] = '\0';
- fd = popen(file, "r");
if (fd)
{
if (fgets(buf, sizeof(buf), fd) == NULL)
@@ -295,13 +292,10 @@ get_prompt(promptStatus_t status, ConditionalStack cstack)
/* interpolate variable */
case ':':
{
- char *name;
+ int nameend = strcspn(p + 1, ":");
+ char *name = pnstrdup(p + 1, nameend);
const char *val;
- int nameend;
- name = pg_strdup(p + 1);
- nameend = strcspn(name, ":");
- name[nameend] = '\0';
val = GetVariable(pset.vars, name);
if (val)
strlcpy(buf, val, sizeof(buf));
diff --git a/src/bin/scripts/common.c b/src/bin/scripts/common.c
index d2a7547441..d919c1cc0b 100644
--- a/src/bin/scripts/common.c
+++ b/src/bin/scripts/common.c
@@ -352,8 +352,7 @@ splitTableColumnsSpec(const char *spec, int encoding,
else
cp += PQmblen(cp, encoding);
}
- *table = pg_strdup(spec);
- (*table)[cp - spec] = '\0'; /* no strndup */
+ *table = pnstrdup(spec, cp - spec);
*columns = cp;
}
diff --git a/src/common/fe_memutils.c b/src/common/fe_memutils.c
index ce99b4f4da..2bc6606b80 100644
--- a/src/common/fe_memutils.c
+++ b/src/common/fe_memutils.c
@@ -142,6 +142,33 @@ pstrdup(const char *in)
return pg_strdup(in);
}
+char *
+pnstrdup(const char *in, Size size)
+{
+ char *tmp;
+ int len;
+
+ if (!in)
+ {
+ fprintf(stderr,
+ _("cannot duplicate null pointer (internal error)\n"));
+ exit(EXIT_FAILURE);
+ }
+
+ len = strnlen(in, size);
+ tmp = malloc(len + 1);
+ if (tmp == NULL)
+ {
+ fprintf(stderr, _("out of memory\n"));
+ exit(EXIT_FAILURE);
+ }
+
+ memcpy(tmp, in, len);
+ tmp[len] = '\0';
+
+ return tmp;
+}
+
void *
repalloc(void *pointer, Size size)
{
diff --git a/src/include/common/fe_memutils.h b/src/include/common/fe_memutils.h
index a1e5940d31..3181ee17dd 100644
--- a/src/include/common/fe_memutils.h
+++ b/src/include/common/fe_memutils.h
@@ -31,6 +31,7 @@ extern void pg_free(void *pointer);
/* Equivalent functions, deliberately named the same as backend functions */
extern char *pstrdup(const char *in);
+extern char *pnstrdup(const char *in, Size size);
extern void *palloc(Size size);
extern void *palloc0(Size size);
extern void *palloc_extended(Size size, int flags);
diff --git a/src/interfaces/ecpg/compatlib/informix.c b/src/interfaces/ecpg/compatlib/informix.c
index a7bbeb9223..b2a19a1dd3 100644
--- a/src/interfaces/ecpg/compatlib/informix.c
+++ b/src/interfaces/ecpg/compatlib/informix.c
@@ -175,25 +175,6 @@ deccopy(decimal *src, decimal *target)
memcpy(target, src, sizeof(decimal));
}
-static char *
-ecpg_strndup(const char *str, size_t len)
-{
- size_t real_len = strlen(str);
- int use_len = (int) ((real_len > len) ? len : real_len);
-
- char *new = malloc(use_len + 1);
-
- if (new)
- {
- memcpy(new, str, use_len);
- new[use_len] = '\0';
- }
- else
- errno = ENOMEM;
-
- return new;
-}
-
int
deccvasc(const char *cp, int len, decimal *np)
{
@@ -205,7 +186,7 @@ deccvasc(const char *cp, int len, decimal *np)
if (risnull(CSTRINGTYPE, cp))
return 0;
- str = ecpg_strndup(cp, len); /* decimal_in always converts the complete
+ str = pnstrdup(cp, len); /* decimal_in always converts the complete
* string */
if (!str)
ret = ECPG_INFORMIX_NUM_UNDERFLOW;
--
2.20.1
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To: pgsql-hackers@postgresql.org
Cc: alvherre@2ndquadrant.com, tgl@sss.pgh.pa.us, andres@anarazel.de, pgsql-hackers@lists.postgresql.org
Subject: Re: adding strndup
In-Reply-To: <20191204220146.GA28850@alvherre.pgsql>
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