1 files changed, 134 insertions, 0 deletions
diff --git a/popen2.c b/popen2.c
index 3434d51..403c324 100644
--- a/popen2.c
+++ b/popen2.c
@@ -0,0 +1,134 @@
+#include"popen2.h"
+#include<errno.h>
+#include<stdlib.h>
+#include<sys/wait.h>
+#include<unistd.h>
+
+#define CLEANUP_PIPE(pipe) close((pipe)[0]); close((pipe)[1])
+
+//https://github.com/iximiuz/popen2
+//https://iximiuz.com/en/posts/how-to-on-processes/
+
+typedef struct files_t files_t;
+
+struct files_chain_t {
+    files_t files;
+    pid_t pid;
+    struct files_chain_t *next;
+};
+typedef struct files_chain_t files_chain_t;
+
+static files_chain_t *files_chain;
+
+static int _do_popen2(files_chain_t *link, const char *command)
+{
+    int child_in[2];
+    int child_out[2];
+    if (0 != pipe(child_in)) {
+        return -1;
+    }
+    if (0 != pipe(child_out)) {
+        CLEANUP_PIPE(child_in);
+        return -1;
+    }
+
+    pid_t cpid = link->pid = fork();
+    if (0 > cpid) {
+       CLEANUP_PIPE(child_in);
+       CLEANUP_PIPE(child_out);
+       return -1;
+    }
+    if (0 == cpid) {
+        if (0 > dup2(child_in[0], 0) || 0 > dup2(child_out[1], 1)) {
+            _Exit(127);
+        }
+        CLEANUP_PIPE(child_in);
+        CLEANUP_PIPE(child_out);
+
+        for (files_chain_t *p = files_chain; p; p = p->next) {
+            int fd_in = fileno(p->files.in);
+            if (fd_in != 0) {
+                close(fd_in);
+            }
+            int fd_out = fileno(p->files.out);
+            if (fd_out != 1) {
+                close(fd_out);
+            }
+        }
+
+        execl("/bin/sh", "sh", "-c", command, (char *) NULL);
+        _Exit(127);
+    }
+
+    close(child_in[0]);
+    close(child_out[1]);
+    link->files.in = fdopen(child_in[1], "w");
+    link->files.out = fdopen(child_out[0], "r");
+    return 0;
+}
+
+/**
+ * NAME
+ *     popen2 -- bidirectional popen()
+ *
+ * DESCRIPTION
+ *     popen2(const char *command) opens two pipes, forks a child process,
+ *     then binds the pipes to its stdin and stdout and execve shell to
+ *     execute given command.
+ *
+ * RETURN VALUES:
+ *     On success it returns a pointer to the struct with two fields
+ *     { FILE *in; FILE *out; }. The struct should be released via pclose2()
+ *     call. On failure returns NULL, check errno for more informaion about
+ *     the error.
+ */
+files_t *popen2(const char *command)
+{
+    files_chain_t *link = (files_chain_t *) malloc(sizeof (files_chain_t));
+    if (NULL == link) {
+        return NULL;
+    }
+
+    if (0 > _do_popen2(link, command)) {
+        free(link);
+        return NULL;
+    }
+
+    link->next = files_chain;
+    files_chain = link;
+    return (files_t *) link;
+}
+
+int pclose2(files_t *fp) {
+    files_chain_t **p = &files_chain;
+    int found = 0;
+    while (*p) {
+        if (*p == (files_chain_t *) fp) {
+            *p = (*p)->next;
+            found = 1;
+            break;
+        }
+        p = &(*p)->next;
+    }
+
+    if (!found) {
+        return -1;
+    }
+    if (0 > fclose(fp->in) || 0 > fclose(fp->out)) {
+        free((files_chain_t *) fp);
+        return -1;
+    }
+
+    int status = -1;
+    pid_t wait_pid;
+    do {
+        wait_pid = waitpid(((files_chain_t *) fp)->pid, &status, 0);
+    } while (-1 == wait_pid && EINTR == errno);
+
+    free((files_chain_t *) fp);
+
+    if (wait_pid == -1) {
+        return -1;
+    }
+    return status;
+}