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Subject[PATCH v4 2/3] trace-cmd: Remove the die() call from read_proc()
Date
As trace-stack.c's read_proc() function is going to be used by trace-cmd stat,
we don't want it to make the program die in case something went wrong.
Therefore, this simple patch makes read_proc() to just return -1 in case the
proc file was empty or read() failed with an error, instead of using die().

Signed-off-by: Vladislav Valtchev (VMware) <vladislav.valtchev@gmail.com>
---
trace-stack.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/trace-stack.c b/trace-stack.c
index fada62d..3e1e41b 100644
--- a/trace-stack.c
+++ b/trace-stack.c
@@ -79,7 +79,7 @@ static int read_proc(int *status)
close(fd);

if (n <= 0)
- die("error reading %s", PROC_FILE);
+ return -1;

if (n >= sizeof(buf))
return -1;
@@ -101,6 +101,7 @@ static void change_stack_tracer_status(unsigned new_status)
{
char buf[1];
int status;
+ int ret;
int fd;
int n;

@@ -109,7 +110,11 @@ static void change_stack_tracer_status(unsigned new_status)
return;
}

- if (read_proc(&status) > 0 && status == new_status)
+ ret = read_proc(&status);
+ if (ret < 0)
+ die("error reading %s", PROC_FILE);
+
+ if (ret > 0 && status == new_status)
return; /* nothing to do */

fd = open(PROC_FILE, O_WRONLY);
--
2.14.1
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