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authorAndrew Burgess <aburgess@redhat.com>2023-09-27 17:18:01 +0100
committerAndrew Burgess <aburgess@redhat.com>2023-10-06 13:02:36 +0100
commit7663126c0b8246754990ce57a2c8432c2d0e4cc9 (patch)
tree6fd62e0c6bbf1e4797f67e18fd71f0490db1789f /gdbserver
parentf1f0a06d5b34231edd75fbd71a3be79097437f62 (diff)
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gdbserver: fix handling of trailing empty argument
When I posted the previous patch for review Andreas Schwab pointed out that passing a trailing empty argument also doesn't work. The fix for this is in the same area of code as the previous patch, but is sufficiently different that I felt it deserved a patch of its own. I noticed that passing arguments containing single quotes to gdbserver didn't work correctly: gdb -ex 'set sysroot' --args /tmp/show-args Reading symbols from /tmp/show-args... (gdb) target extended-remote | gdbserver --once --multi - /tmp/show-args Remote debugging using | gdbserver --once --multi - /tmp/show-args stdin/stdout redirected Process /tmp/show-args created; pid = 176054 Remote debugging using stdio Reading symbols from /lib64/ld-linux-x86-64.so.2... (No debugging symbols found in /lib64/ld-linux-x86-64.so.2) 0x00007ffff7fd3110 in _start () from /lib64/ld-linux-x86-64.so.2 (gdb) set args abc "" (gdb) run The program being debugged has been started already. Start it from the beginning? (y or n) y Starting program: /tmp/show-args \' stdin/stdout redirected Process /tmp/show-args created; pid = 176088 2 args are: /tmp/show-args abc Done. [Inferior 1 (process 176088) exited normally] (gdb) target native Done. Use the "run" command to start a process. (gdb) run Starting program: /tmp/show-args \' 2 args are: /tmp/show-args abc Done. [Inferior 1 (process 176095) exited normally] (gdb) q The 'shows-args' program used here just prints the arguments passed to the inferior. Notice that when starting the inferior using the extended-remote target there is only a single argument 'abc', while when using the native target there is a second argument, the blank line, representing the empty argument. The problem here is that the vRun packet coming from GDB looks like this (I've removing the trailing checksum): $vRun;PROGRAM_NAME;616263; If we compare this to a packet with only a single argument and no trailing empty argument: $vRun;PROGRAM_NAME;616263 Notice the lack of the trailing ';' character here. The problem is that gdbserver processes this string in a loop. At each point we maintain a pointer to the character just after a ';', and then we process everything up to either the next ';' character, or to the end of the string. We break out of this loop when the character we start with (in that loop iteration) is the null-character. This means in the trailing empty argument case, we abort the loop before doing anything with the empty argument. In this commit I've updated the loop, we now break out using a 'break' statement at the end of the loop if the (sub-)string we just processed was empty, with this change we now notice the trailing empty argument. I've updated the test case to cover this issue. Approved-By: Tom Tromey <tom@tromey.com>
Diffstat (limited to 'gdbserver')
-rw-r--r--gdbserver/server.cc8
1 files changed, 5 insertions, 3 deletions
diff --git a/gdbserver/server.cc b/gdbserver/server.cc
index 496b9be..d78eb5a 100644
--- a/gdbserver/server.cc
+++ b/gdbserver/server.cc
@@ -2969,7 +2969,9 @@ handle_v_run (char *own_buf)
char *new_program_name = NULL;
int i;
- for (i = 0, p = own_buf + strlen ("vRun;"); *p; p = next_p, ++i)
+ for (i = 0, p = own_buf + strlen ("vRun;");
+ /* Exit condition is at the end of the loop. */;
+ p = next_p + 1, ++i)
{
next_p = strchr (p, ';');
if (next_p == NULL)
@@ -3032,8 +3034,8 @@ handle_v_run (char *own_buf)
new_argv.push_back (full_arg);
xfree (arg);
}
- if (*next_p)
- next_p++;
+ if (*next_p == '\0')
+ break;
}
if (new_program_name == NULL)