Signed-off-by: Nguyễn Thái Ngọc Duy <[email protected]>
---
Perhaps this will help the getenv bug hunting (I assume we do the
hunting on Linux platform only). So far it catches this and is stuck
at getenv in git_pager().
diff --git a/exec_cmd.c b/exec_cmd.c
index 125fa6f..d8be5ce 100644
--- a/exec_cmd.c
+++ b/exec_cmd.c
@@ -97,7 +97,7 @@ static void add_path(struct strbuf *out, const char *path)
void setup_path(void)
{
- const char *old_path = getenv("PATH");
+ char *old_path = xstrdup(getenv("PATH"));
struct strbuf new_path = STRBUF_INIT;
add_path(&new_path, git_exec_path());
@@ -110,6 +110,7 @@ void setup_path(void)
setenv("PATH", new_path.buf, 1);
+ free(old_path);
strbuf_release(&new_path);
}
contrib/getenv/Makefile | 2 ++
contrib/getenv/getenv.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 69 insertions(+)
create mode 100644 contrib/getenv/Makefile
create mode 100644 contrib/getenv/getenv.c
diff --git a/contrib/getenv/Makefile b/contrib/getenv/Makefile
new file mode 100644
index 0000000..4881b85
--- /dev/null
+++ b/contrib/getenv/Makefile
@@ -0,0 +1,2 @@
+getenv.so: getenv.c
+ $(CC) -g -shared -fPIC -ldl -o $@ $<
diff --git a/contrib/getenv/getenv.c b/contrib/getenv/getenv.c
new file mode 100644
index 0000000..e351e10
--- /dev/null
+++ b/contrib/getenv/getenv.c
@@ -0,0 +1,67 @@
+#include <gnu/lib-names.h>
+#include <sys/mman.h>
+#include <dlfcn.h>
+#include <execinfo.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+/* Global symbols for easy access from gdb */
+static char *getenv_current;
+static char *getenv_prev;
+
+/*
+ * Intercept standard getenv() via LD_PRELOAD. The return value is
+ * made inaccessible by the next getenv() call. This helps catch
+ * places that ignore the statement "The string pointed to may be
+ * overwritten by a subsequent call to getenv()" [1].
+ *
+ * The backtrace is appended after the env string, which may be
+ * helpful to identify where this getenv() is called in a core dump.
+ *
+ * [1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/getenv.html
+ */
+char *getenv(const char *name)
+{
+ static char *(*libc_getenv)(const char*);
+ char *value;
+
+ if (!libc_getenv) {
+ void *libc = dlopen(LIBC_SO, RTLD_LAZY);
+ libc_getenv = dlsym(libc, "getenv");
+ }
+ if (getenv_current) {
+ mprotect(getenv_current, strlen(getenv_current) + 1, PROT_NONE);
+ getenv_prev = getenv_current;
+ getenv_current = NULL;
+ }
+
+ value = libc_getenv(name);
+ if (value) {
+ int len = strlen(value) + 1;
+ int backtrace_len = 0;
+ void *buffer[100];
+ char **symbols;
+ int i, n;
+
+ n = backtrace(buffer, 100);
+ symbols = backtrace_symbols(buffer, n);
+ if (symbols) {
+ for (i = 0;i < n; i++)
+ backtrace_len += strlen(symbols[i]) + 1; /* \n
*/
+ backtrace_len++; /* NULL */
+ }
+
+ getenv_current = mmap(NULL, len + backtrace_len, PROT_READ |
PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
+ memcpy(getenv_current, value, len);
+ value = getenv_current;
+
+ if (symbols) {
+ char *p = getenv_current + len;
+ for (i = 0; i < n; i++)
+ p += sprintf(p, "%s\n", symbols[i]);
+ }
+ }
+ return value;
+}
--
1.8.0.rc2.23.g1fb49df
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