On 2019-Dec-04, Alvaro Herrera wrote: > On 2019-Dec-04, Tom Lane wrote: > > > Andres Freund <and...@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
>From c4dc0fd76e86bf97cb612bafe30847c47b77813e Mon Sep 17 00:00:00 2001 From: Alvaro Herrera <alvhe...@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
