1 files changed, 134 insertions, 0 deletions
diff --git a/src/xspawn.h b/src/xspawn.h
new file mode 100644
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--- /dev/null
+++ b/src/xspawn.h
@@ -0,0 +1,134 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+/**
+ * A process-spawning library inspired by posix_spawn().
+ */
+
+#ifndef BFS_XSPAWN_H
+#define BFS_XSPAWN_H
+
+#include "prelude.h"
+#include <sys/resource.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#if _POSIX_SPAWN > 0
+#  include <spawn.h>
+#endif
+
+/**
+ * bfs_spawn() flags.
+ */
+enum bfs_spawn_flags {
+	/** Use the PATH variable to resolve the executable (like execvp()). */
+	BFS_SPAWN_USE_PATH  = 1 << 0,
+	/** Whether posix_spawn() can be used. */
+	BFS_SPAWN_USE_POSIX = 1 << 1,
+};
+
+/**
+ * bfs_spawn() attributes, controlling the context of the new process.
+ */
+struct bfs_spawn {
+	/** Spawn flags. */
+	enum bfs_spawn_flags flags;
+
+	/** Linked list of actions. */
+	struct bfs_spawn_action *head;
+	struct bfs_spawn_action **tail;
+
+#if _POSIX_SPAWN > 0
+	/** posix_spawn() context, for when we can use it. */
+	posix_spawn_file_actions_t actions;
+	posix_spawnattr_t attr;
+#endif
+};
+
+/**
+ * Create a new bfs_spawn() context.
+ *
+ * @return
+ *         0 on success, -1 on failure.
+ */
+int bfs_spawn_init(struct bfs_spawn *ctx);
+
+/**
+ * Destroy a bfs_spawn() context.
+ *
+ * @return
+ *         0 on success, -1 on failure.
+ */
+int bfs_spawn_destroy(struct bfs_spawn *ctx);
+
+/**
+ * Add an open() action to a bfs_spawn() context.
+ *
+ * @return
+ *         0 on success, -1 on failure.
+ */
+int bfs_spawn_addopen(struct bfs_spawn *ctx, int fd, const char *path, int flags, mode_t mode);
+
+/**
+ * Add a close() action to a bfs_spawn() context.
+ *
+ * @return
+ *         0 on success, -1 on failure.
+ */
+int bfs_spawn_addclose(struct bfs_spawn *ctx, int fd);
+
+/**
+ * Add a dup2() action to a bfs_spawn() context.
+ *
+ * @return
+ *         0 on success, -1 on failure.
+ */
+int bfs_spawn_adddup2(struct bfs_spawn *ctx, int oldfd, int newfd);
+
+/**
+ * Add an fchdir() action to a bfs_spawn() context.
+ *
+ * @return
+ *         0 on success, -1 on failure.
+ */
+int bfs_spawn_addfchdir(struct bfs_spawn *ctx, int fd);
+
+/**
+ * Apply setrlimit() to a bfs_spawn() context.
+ *
+ * @return
+ *         0 on success, -1 on failure.
+ */
+int bfs_spawn_setrlimit(struct bfs_spawn *ctx, int resource, const struct rlimit *rl);
+
+/**
+ * Spawn a new process.
+ *
+ * @param exe
+ *         The executable to run.
+ * @param ctx
+ *         The context for the new process.
+ * @param argv
+ *         The arguments for the new process.
+ * @param envp
+ *         The environment variables for the new process (NULL for the current
+ *         environment).
+ * @return
+ *         The PID of the new process, or -1 on error.
+ */
+pid_t bfs_spawn(const char *exe, const struct bfs_spawn *ctx, char **argv, char **envp);
+
+/**
+ * Look up an executable in the current PATH, as BFS_SPAWN_USE_PATH or execvp()
+ * would do.
+ *
+ * @param exe
+ *         The name of the binary to execute.  Bare names without a '/' will be
+ *         searched on the provided PATH.
+ * @return
+ *         The full path to the executable, which should be free()'d, or NULL on
+ *         failure.
+ */
+char *bfs_spawn_resolve(const char *exe);
+
+#endif // BFS_XSPAWN_H