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fa64a2fdbe
Refactor, into a common function, the version and capability negotiation done when invoking a long-running process as a clean or smudge filter. This will be useful for other Git code that needs to interact similarly with a long-running process. As you can see in the change to t0021, this commit changes the error message reported when the long-running process does not introduce itself with the expected "server"-terminated line. Originally, the error message reports that the filter "does not support filter protocol version 2", differentiating between the old single-file filter protocol and the new multi-file filter protocol - I have updated it to something more generic and useful. Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
98 lines
3.2 KiB
C
98 lines
3.2 KiB
C
#ifndef SUBPROCESS_H
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#define SUBPROCESS_H
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#include "git-compat-util.h"
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#include "hashmap.h"
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#include "run-command.h"
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/*
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* The sub-process API makes it possible to run background sub-processes
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* for the entire lifetime of a Git invocation. If Git needs to communicate
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* with an external process multiple times, then this can reduces the process
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* invocation overhead. Git and the sub-process communicate through stdin and
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* stdout.
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*
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* The sub-processes are kept in a hashmap by command name and looked up
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* via the subprocess_find_entry function. If an existing instance can not
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* be found then a new process should be created and started. When the
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* parent git command terminates, all sub-processes are also terminated.
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*
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* This API is based on the run-command API.
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*/
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/* data structures */
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/* Members should not be accessed directly. */
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struct subprocess_entry {
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struct hashmap_entry ent; /* must be the first member! */
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const char *cmd;
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struct child_process process;
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};
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struct subprocess_capability {
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const char *name;
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/*
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* subprocess_handshake will "|=" this value to supported_capabilities
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* if the server reports that it supports this capability.
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*/
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unsigned int flag;
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};
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/* subprocess functions */
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/* Function to test two subprocess hashmap entries for equality. */
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extern int cmd2process_cmp(const void *unused_cmp_data,
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const struct subprocess_entry *e1,
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const struct subprocess_entry *e2,
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const void *unused_keydata);
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/*
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* User-supplied function to initialize the sub-process. This is
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* typically used to negotiate the interface version and capabilities.
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*/
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typedef int(*subprocess_start_fn)(struct subprocess_entry *entry);
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/* Start a subprocess and add it to the subprocess hashmap. */
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int subprocess_start(struct hashmap *hashmap, struct subprocess_entry *entry, const char *cmd,
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subprocess_start_fn startfn);
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/* Kill a subprocess and remove it from the subprocess hashmap. */
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void subprocess_stop(struct hashmap *hashmap, struct subprocess_entry *entry);
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/* Find a subprocess in the subprocess hashmap. */
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struct subprocess_entry *subprocess_find_entry(struct hashmap *hashmap, const char *cmd);
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/* subprocess helper functions */
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/* Get the underlying `struct child_process` from a subprocess. */
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static inline struct child_process *subprocess_get_child_process(
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struct subprocess_entry *entry)
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{
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return &entry->process;
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}
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/*
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* Perform the version and capability negotiation as described in the "Long
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* Running Filter Process" section of the gitattributes documentation using the
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* given requested versions and capabilities. The "versions" and "capabilities"
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* parameters are arrays terminated by a 0 or blank struct.
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*
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* This function is typically called when a subprocess is started (as part of
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* the "startfn" passed to subprocess_start).
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*/
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int subprocess_handshake(struct subprocess_entry *entry,
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const char *welcome_prefix,
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int *versions,
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int *chosen_version,
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struct subprocess_capability *capabilities,
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unsigned int *supported_capabilities);
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/*
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* Helper function that will read packets looking for "status=<foo>"
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* key/value pairs and return the value from the last "status" packet
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*/
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int subprocess_read_status(int fd, struct strbuf *status);
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#endif
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