merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

1 files changed, 89 insertions, 0 deletions

diff --git a/third_party/git/strvec.h b/third_party/git/strvec.h
new file mode 100644
index 0000000000..fdcad75b45
--- /dev/null
+++ b/third_party/git/strvec.h
@@ -0,0 +1,89 @@
+#ifndef STRVEC_H
+#define STRVEC_H
+
+/**
+ * The strvec API allows one to dynamically build and store
+ * NULL-terminated arrays of strings. A strvec maintains the invariant that the
+ * `items` member always points to a non-NULL array, and that the array is
+ * always NULL-terminated at the element pointed to by `items[nr]`. This
+ * makes the result suitable for passing to functions expecting to receive
+ * argv from main().
+ *
+ * The string-list API (documented in string-list.h) is similar, but cannot be
+ * used for these purposes; instead of storing a straight string pointer,
+ * it contains an item structure with a `util` field that is not compatible
+ * with the traditional argv interface.
+ *
+ * Each `strvec` manages its own memory. Any strings pushed into the
+ * array are duplicated, and all memory is freed by strvec_clear().
+ */
+
+extern const char *empty_strvec[];
+
+/**
+ * A single array. This should be initialized by assignment from
+ * `STRVEC_INIT`, or by calling `strvec_init`. The `items`
+ * member contains the actual array; the `nr` member contains the
+ * number of elements in the array, not including the terminating
+ * NULL.
+ */
+struct strvec {
+	const char **v;
+	int nr;
+	int alloc;
+};
+
+#define STRVEC_INIT { empty_strvec, 0, 0 }
+
+/**
+ * Initialize an array. This is no different than assigning from
+ * `STRVEC_INIT`.
+ */
+void strvec_init(struct strvec *);
+
+/* Push a copy of a string onto the end of the array. */
+const char *strvec_push(struct strvec *, const char *);
+
+/**
+ * Format a string and push it onto the end of the array. This is a
+ * convenience wrapper combining `strbuf_addf` and `strvec_push`.
+ */
+__attribute__((format (printf,2,3)))
+const char *strvec_pushf(struct strvec *, const char *fmt, ...);
+
+/**
+ * Push a list of strings onto the end of the array. The arguments
+ * should be a list of `const char *` strings, terminated by a NULL
+ * argument.
+ */
+LAST_ARG_MUST_BE_NULL
+void strvec_pushl(struct strvec *, ...);
+
+/* Push a null-terminated array of strings onto the end of the array. */
+void strvec_pushv(struct strvec *, const char **);
+
+/**
+ * Remove the final element from the array. If there are no
+ * elements in the array, do nothing.
+ */
+void strvec_pop(struct strvec *);
+
+/* Splits by whitespace; does not handle quoted arguments! */
+void strvec_split(struct strvec *, const char *);
+
+/**
+ * Free all memory associated with the array and return it to the
+ * initial, empty state.
+ */
+void strvec_clear(struct strvec *);
+
+/**
+ * Disconnect the `items` member from the `strvec` struct and
+ * return it. The caller is responsible for freeing the memory used
+ * by the array, and by the strings it references. After detaching,
+ * the `strvec` is in a reinitialized state and can be pushed
+ * into again.
+ */
+const char **strvec_detach(struct strvec *);
+
+#endif /* STRVEC_H */