Introduced an API to collect the core from an unrelated process

CMakeLists.txt

@@ -12,6 +12,8 @@ set(COREDUMPER_SRC_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
 
 add_subdirectory(src)
 
+add_subdirectory(tool)
+
 include(CTest)
 if(BUILD_TESTING)
   enable_testing()

include/coredumper/coredumper.h

@@ -36,6 +36,7 @@
 #define _COREDUMP_H
 
 #include <stddef.h>
+#include <sys/types.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -105,6 +106,11 @@ struct CoreDumpParameters {
  */
 #define COREDUMPER_FLAG_LIMITED_BY_PRIORITY 2
 
+/* The core file is requested for an external process, By default we try to
+ * collect the core from self.
+ */
+#define COREDUMPER_FLAG_EXTERNAL_PROCESS 4
+
 /* Try compressing with either bzip2, gzip, or compress. If all of those fail,
  * fall back on generating an uncompressed file.
  */
@@ -166,6 +172,14 @@ int GetCompressedCoreDump(const struct CoredumperCompressor compressors[],
  */
 int WriteCoreDump(const char *file_name);
 
+/* Writes the core file of a process with pid to disk. This is a convenience
+ * method wrapping GetCoreDump(). If a core file could not be generated
+ * for any reason, -1 is returned and errno is set appropriately.
+ * On success, zero is returned.
+ */
+int WriteCoreDumpOfPID(struct CoreDumpParameters *params,
+                       const char *file_name, pid_t pid);
+
 /* Writes a core dump to the given file with the given parameters.           */
 int WriteCoreDumpWith(const struct CoreDumpParameters *params, const char *file_name);
 

src/coredumper.c

@@ -178,6 +178,25 @@ int WriteCoreDump(const char *file_name) {
   return WriteCoreDumpFunction(&frame, &params, file_name);
 }
 
+/*
+ * This variant collects the core from a process with pid.
+ * Useful to collect core from un-related process, this assumes that
+ * the caller has the permission or privilege to trace 'pid' process.
+ */
+int WriteCoreDumpOfPID(struct CoreDumpParameters *params,
+                       const char *file_name, pid_t pid) {
+  Frame f;
+
+  /*
+   * Frame cannot be used to retrieve register value for an external process
+   * we are just using it to pass the pid below.
+   */
+  f.tid = pid;
+
+  SetCoreDumpParameter(params, flags, COREDUMPER_FLAG_EXTERNAL_PROCESS);
+  return ListAllThreadsOfPid(&f, pid, InternalGetCoreDump, params, file_name, getenv("PATH"));
+}
+
 int WriteCoreDumpWith(const struct CoreDumpParameters *params, const char *file_name) {
   FRAME(frame);
   return WriteCoreDumpFunction(&frame, params, file_name);