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#include "git-compat-util.h"
#include "hashmap.h"
#include "run-command.h"
* The sub-process API makes it possible to run background sub-processes
* for the entire lifetime of a Git invocation. If Git needs to communicate
* with an external process multiple times, then this can reduces the process
* invocation overhead. Git and the sub-process communicate through stdin and
* stdout.
* The sub-processes are kept in a hashmap by command name and looked up
* via the subprocess_find_entry function. If an existing instance can not
* be found then a new process should be created and started. When the
* parent git command terminates, all sub-processes are also terminated.
* This API is based on the run-command API.
/* data structures */
/* Members should not be accessed directly. */
struct subprocess_entry {
struct hashmap_entry ent;
const char *cmd;
struct child_process process;
struct subprocess_capability {
const char *name;
* subprocess_handshake will "|=" this value to supported_capabilities
* if the server reports that it supports this capability.
unsigned int flag;
/* subprocess functions */
/* Function to test two subprocess hashmap entries for equality. */
int cmd2process_cmp(const void *unused_cmp_data,
const struct hashmap_entry *e,
const struct hashmap_entry *entry_or_key,
const void *unused_keydata);
* User-supplied function to initialize the sub-process. This is
* typically used to negotiate the interface version and capabilities.
typedef int(*subprocess_start_fn)(struct subprocess_entry *entry);
/* Start a subprocess and add it to the subprocess hashmap. */
int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
subprocess_start_fn startfn);
/* Kill a subprocess and remove it from the subprocess hashmap. */
void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry);
/* Find a subprocess in the subprocess hashmap. */
struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd);
/* subprocess helper functions */
/* Get the underlying `struct child_process` from a subprocess. */
static inline struct child_process *subprocess_get_child_process(
struct subprocess_entry *entry)
return &entry->process;
* Perform the version and capability negotiation as described in the
* "Handshake" section of long-running-process-protocol.txt using the
* given requested versions and capabilities. The "versions" and "capabilities"
* parameters are arrays terminated by a 0 or blank struct.
* This function is typically called when a subprocess is started (as part of
* the "startfn" passed to subprocess_start).
int subprocess_handshake(struct subprocess_entry *entry,
const char *welcome_prefix,
int *versions,
int *chosen_version,
struct subprocess_capability *capabilities,
unsigned int *supported_capabilities);
* Helper function that will read packets looking for "status=<foo>"
* key/value pairs and return the value from the last "status" packet
int subprocess_read_status(int fd, struct strbuf *status);