* [PATCH 2/2] Use asprintf() to allocate strings
@ 2026-01-16 18:55 eugene.loh
2026-01-16 22:15 ` Kris Van Hees
0 siblings, 1 reply; 2+ messages in thread
From: eugene.loh @ 2026-01-16 18:55 UTC (permalink / raw)
To: dtrace, dtrace-devel
From: Eugene Loh <eugene.loh@oracle.com>
Earlier patches have slowly replaced constructs like:
int len;
len = snprintf(NULL, 0, format, args) + 1;
buf = malloc(len);
snprintf(buf, len, format, args);
with the more compact:
asprintf(&buf, format, args);
Replace the remaining instances of the bulkier construct.
Note that dt_conf_init() continues to compute a buffer length and
allocate a buffer, since that buffer will be reused multiple times.
Signed-off-by: Eugene Loh <eugene.loh@oracle.com>
---
libdtrace/dt_link.c | 17 +++++++----------
libdtrace/dt_probe.c | 11 +++--------
libdtrace/dt_prov_dtrace.c | 12 +++---------
3 files changed, 13 insertions(+), 27 deletions(-)
diff --git a/libdtrace/dt_link.c b/libdtrace/dt_link.c
index c9e0ea5fe..ffa16d9a4 100644
--- a/libdtrace/dt_link.c
+++ b/libdtrace/dt_link.c
@@ -1,6 +1,6 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2008, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2026, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
@@ -416,7 +416,6 @@ dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags,
char drti[PATH_MAX], symvers[PATH_MAX];
int fd, i, cur;
char *cmd;
- size_t len;
int ret = 0, status = 0;
/*
@@ -426,6 +425,7 @@ dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags,
*/
if (pgp == NULL) {
const char *fmt = "%s -o %s -r";
+ size_t len;
len = snprintf(NULL, 0, fmt, dtp->dt_ld_path, file) + 1;
@@ -521,15 +521,12 @@ dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags,
}
snprintf(symvers, sizeof (symvers), "%s/drti/drti-vers", libdir->dir_path);
- len = snprintf(NULL, 0, fmt, dtp->dt_ld_path, emu, file,
- symvers, fd, drti) + 1;
+ asprintf(&cmd, fmt, dtp->dt_ld_path, emu, file, symvers, fd,
+ drti);
+ status = system(cmd);
+ free(cmd);
- cmd = alloca(len);
-
- (void) snprintf(cmd, len, fmt, dtp->dt_ld_path, emu, file,
- symvers, fd, drti);
-
- if ((status = system(cmd)) == -1) {
+ if (status == -1) {
ret = dt_link_error(dtp, NULL, -1,
"failed to run %s: %s", dtp->dt_ld_path,
strerror(errno));
diff --git a/libdtrace/dt_probe.c b/libdtrace/dt_probe.c
index 65316f515..86353893f 100644
--- a/libdtrace/dt_probe.c
+++ b/libdtrace/dt_probe.c
@@ -1,6 +1,6 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2006, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2026, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
@@ -475,15 +475,9 @@ dt_probe_tag(dt_probe_t *prp, uint_t argn, dt_node_t *dnp)
{
dtrace_hdl_t *dtp = prp->prov->pv_hdl;
dtrace_typeinfo_t dtt;
- size_t len;
char *tag;
- len = snprintf(NULL, 0, "__dtrace_%s___%s_arg%u",
- prp->prov->desc.dtvd_name, prp->pr_name, argn);
-
- tag = alloca(len + 1);
-
- snprintf(tag, len + 1, "__dtrace_%s___%s_arg%u",
+ asprintf(&tag, "__dtrace_%s___%s_arg%u",
prp->prov->desc.dtvd_name, prp->pr_name, argn);
if (dtrace_lookup_by_type(dtp, DTRACE_OBJ_DDEFS, tag, &dtt) != 0) {
@@ -498,6 +492,7 @@ dt_probe_tag(dt_probe_t *prp, uint_t argn, dt_node_t *dnp)
tag, ctf_errmsg(ctf_errno(dtt.dtt_ctfp)));
}
}
+ free(tag);
memset(dnp, 0, sizeof(dt_node_t));
dnp->dn_kind = DT_NODE_TYPE;
diff --git a/libdtrace/dt_prov_dtrace.c b/libdtrace/dt_prov_dtrace.c
index 102afd84e..d417a864b 100644
--- a/libdtrace/dt_prov_dtrace.c
+++ b/libdtrace/dt_prov_dtrace.c
@@ -232,7 +232,6 @@ static int attach(dtrace_hdl_t *dtp, const dt_probe_t *prp, int bpf_fd)
char *spec;
char *fn;
FILE *f;
- size_t len;
int fd, rc = -1;
/* get a uprobe specification for this probe */
@@ -252,16 +251,11 @@ static int attach(dtrace_hdl_t *dtp, const dt_probe_t *prp, int bpf_fd)
return -ENOENT;
/* open format file */
- len = snprintf(NULL, 0, "%s" PROBE_FMT "/format",
- EVENTSFS, PROBE_DATA) + 1;
- fn = dt_alloc(dtp, len);
- if (fn == NULL)
+ if (asprintf(&fn, "%s" PROBE_FMT "/format", EVENTSFS,
+ PROBE_DATA) < 0)
return -ENOENT;
-
- snprintf(fn, len, "%s" PROBE_FMT "/format",
- EVENTSFS, PROBE_DATA);
f = fopen(fn, "r");
- dt_free(dtp, fn);
+ free(fn);
if (f == NULL)
return -ENOENT;
--
2.47.3
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH 2/2] Use asprintf() to allocate strings
2026-01-16 18:55 [PATCH 2/2] Use asprintf() to allocate strings eugene.loh
@ 2026-01-16 22:15 ` Kris Van Hees
0 siblings, 0 replies; 2+ messages in thread
From: Kris Van Hees @ 2026-01-16 22:15 UTC (permalink / raw)
To: eugene.loh; +Cc: dtrace, dtrace-devel
On Fri, Jan 16, 2026 at 01:55:29PM -0500, eugene.loh@oracle.com wrote:
> From: Eugene Loh <eugene.loh@oracle.com>
>
> Earlier patches have slowly replaced constructs like:
> int len;
> len = snprintf(NULL, 0, format, args) + 1;
> buf = malloc(len);
> snprintf(buf, len, format, args);
> with the more compact:
> asprintf(&buf, format, args);
>
> Replace the remaining instances of the bulkier construct.
>
> Note that dt_conf_init() continues to compute a buffer length and
> allocate a buffer, since that buffer will be reused multiple times.
>
> Signed-off-by: Eugene Loh <eugene.loh@oracle.com>
> ---
> libdtrace/dt_link.c | 17 +++++++----------
> libdtrace/dt_probe.c | 11 +++--------
> libdtrace/dt_prov_dtrace.c | 12 +++---------
> 3 files changed, 13 insertions(+), 27 deletions(-)
>
> diff --git a/libdtrace/dt_link.c b/libdtrace/dt_link.c
> index c9e0ea5fe..ffa16d9a4 100644
> --- a/libdtrace/dt_link.c
> +++ b/libdtrace/dt_link.c
> @@ -1,6 +1,6 @@
> /*
> * Oracle Linux DTrace.
> - * Copyright (c) 2008, 2025, Oracle and/or its affiliates. All rights reserved.
> + * Copyright (c) 2008, 2026, Oracle and/or its affiliates. All rights reserved.
> * Licensed under the Universal Permissive License v 1.0 as shown at
> * http://oss.oracle.com/licenses/upl.
> */
> @@ -416,7 +416,6 @@ dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags,
> char drti[PATH_MAX], symvers[PATH_MAX];
> int fd, i, cur;
> char *cmd;
> - size_t len;
> int ret = 0, status = 0;
>
> /*
> @@ -426,6 +425,7 @@ dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags,
> */
> if (pgp == NULL) {
> const char *fmt = "%s -o %s -r";
> + size_t len;
>
> len = snprintf(NULL, 0, fmt, dtp->dt_ld_path, file) + 1;
>
> @@ -521,15 +521,12 @@ dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags,
> }
> snprintf(symvers, sizeof (symvers), "%s/drti/drti-vers", libdir->dir_path);
>
> - len = snprintf(NULL, 0, fmt, dtp->dt_ld_path, emu, file,
> - symvers, fd, drti) + 1;
> + asprintf(&cmd, fmt, dtp->dt_ld_path, emu, file, symvers, fd,
> + drti);
> + status = system(cmd);
> + free(cmd);
>
> - cmd = alloca(len);
> -
> - (void) snprintf(cmd, len, fmt, dtp->dt_ld_path, emu, file,
> - symvers, fd, drti);
> -
> - if ((status = system(cmd)) == -1) {
> + if (status == -1) {
> ret = dt_link_error(dtp, NULL, -1,
> "failed to run %s: %s", dtp->dt_ld_path,
> strerror(errno));
> diff --git a/libdtrace/dt_probe.c b/libdtrace/dt_probe.c
> index 65316f515..86353893f 100644
> --- a/libdtrace/dt_probe.c
> +++ b/libdtrace/dt_probe.c
> @@ -1,6 +1,6 @@
> /*
> * Oracle Linux DTrace.
> - * Copyright (c) 2006, 2025, Oracle and/or its affiliates. All rights reserved.
> + * Copyright (c) 2006, 2026, Oracle and/or its affiliates. All rights reserved.
> * Licensed under the Universal Permissive License v 1.0 as shown at
> * http://oss.oracle.com/licenses/upl.
> */
> @@ -475,15 +475,9 @@ dt_probe_tag(dt_probe_t *prp, uint_t argn, dt_node_t *dnp)
> {
> dtrace_hdl_t *dtp = prp->prov->pv_hdl;
> dtrace_typeinfo_t dtt;
> - size_t len;
> char *tag;
>
> - len = snprintf(NULL, 0, "__dtrace_%s___%s_arg%u",
> - prp->prov->desc.dtvd_name, prp->pr_name, argn);
> -
> - tag = alloca(len + 1);
> -
> - snprintf(tag, len + 1, "__dtrace_%s___%s_arg%u",
> + asprintf(&tag, "__dtrace_%s___%s_arg%u",
> prp->prov->desc.dtvd_name, prp->pr_name, argn);
This one should not be replaced, because if the ctf_add_typedef fails, 'tag'
will never be freed and thus becomes a memory leak. Granted, in that case
dtrace will end with an error message anyway, but still, it is a bit sloppy.
This is why the original code here is using an alloca()... that goes away at
the end of the function scope.
>
> if (dtrace_lookup_by_type(dtp, DTRACE_OBJ_DDEFS, tag, &dtt) != 0) {
> @@ -498,6 +492,7 @@ dt_probe_tag(dt_probe_t *prp, uint_t argn, dt_node_t *dnp)
> tag, ctf_errmsg(ctf_errno(dtt.dtt_ctfp)));
> }
> }
> + free(tag);
>
> memset(dnp, 0, sizeof(dt_node_t));
> dnp->dn_kind = DT_NODE_TYPE;
> diff --git a/libdtrace/dt_prov_dtrace.c b/libdtrace/dt_prov_dtrace.c
> index 102afd84e..d417a864b 100644
> --- a/libdtrace/dt_prov_dtrace.c
> +++ b/libdtrace/dt_prov_dtrace.c
> @@ -232,7 +232,6 @@ static int attach(dtrace_hdl_t *dtp, const dt_probe_t *prp, int bpf_fd)
> char *spec;
> char *fn;
> FILE *f;
> - size_t len;
> int fd, rc = -1;
>
> /* get a uprobe specification for this probe */
> @@ -252,16 +251,11 @@ static int attach(dtrace_hdl_t *dtp, const dt_probe_t *prp, int bpf_fd)
> return -ENOENT;
>
> /* open format file */
> - len = snprintf(NULL, 0, "%s" PROBE_FMT "/format",
> - EVENTSFS, PROBE_DATA) + 1;
> - fn = dt_alloc(dtp, len);
> - if (fn == NULL)
> + if (asprintf(&fn, "%s" PROBE_FMT "/format", EVENTSFS,
> + PROBE_DATA) < 0)
> return -ENOENT;
> -
> - snprintf(fn, len, "%s" PROBE_FMT "/format",
> - EVENTSFS, PROBE_DATA);
> f = fopen(fn, "r");
> - dt_free(dtp, fn);
> + free(fn);
> if (f == NULL)
> return -ENOENT;
>
> --
> 2.47.3
>
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