Integrate linenoise package with web server

In the previous version of console implementation, we tried to integrate
tiny-web-server to enable the ability of processing commands from web
requests. As the result, the package linenoise which is responsible for
command-line auto-complete needs to be disabled during the running time
of tiny-web-server. Because the `line_edit()` function in linenoise.c
doesn't have the ability to handle web requests correctly.

When we start the web server, we use `cmd_select` in console.c and use
`select` system call to monitor web socket file descriptor and stdin_fd
at the same time, however, this ability should present in the
`line_edit` function in linenoise.c so we can process commands from
command-line and from web requests at the same time.

When we start the web server, we use `cmd_select` in console.c and use
`select` function to monitor web socket file descriptor and stdin_fd at
the same time. I re-design the control flow of web request and
command-line input by implement the hook function `web_select()`,
which use the function `select()` to monitor both input file descriptor
 and web file descriptor and modify `line_edit()` to use `web_select()`
so we can process command-line input as normal.

One may wonder why don't we simply modify the function `line_edt()`, the
reason is that linenoise is an upstream package so we only want to do
the miminal changes to this package.

Change change change

change change change

console.c

@@ -560,13 +560,13 @@ static int cmd_select(int nfds,
                       fd_set *exceptfds,
                       struct timeval *timeout)
 {
-    int infd;
     fd_set local_readset;
 
     if (cmd_done())
         return 0;
 
     if (!block_flag) {
+        int infd;
         /* Process any commands in input buffer */
         if (!readfds)
             readfds = &local_readset;
@@ -581,51 +581,18 @@ static int cmd_select(int nfds,
             FD_SET(web_fd, readfds);
 
         if (infd == STDIN_FILENO && prompt_flag) {
-            printf("%s", prompt);
+            char *cmdline = linenoise(prompt);
+            if (cmdline)
+                interpret_cmd(cmdline);
             fflush(stdout);
             prompt_flag = true;
+        } else if (infd != STDIN_FILENO) {
+            char *cmdline = readline();
+            if (cmdline)
+                interpret_cmd(cmdline);
         }
-
-        if (infd >= nfds)
-            nfds = infd + 1;
-        if (web_fd >= nfds)
-            nfds = web_fd + 1;
-    }
-    if (nfds == 0)
-        return 0;
-
-    int result = select(nfds, readfds, writefds, exceptfds, timeout);
-    if (result <= 0)
-        return result;
-
-    infd = buf_stack->fd;
-    if (readfds && FD_ISSET(infd, readfds)) {
-        /* Commandline input available */
-        FD_CLR(infd, readfds);
-        result--;
-
-        set_echo(0);
-        char *cmdline = readline();
-        if (cmdline)
-            interpret_cmd(cmdline);
-    } else if (readfds && FD_ISSET(web_fd, readfds)) {
-        FD_CLR(web_fd, readfds);
-        result--;
-        struct sockaddr_in clientaddr;
-        socklen_t clientlen = sizeof(clientaddr);
-        web_connfd =
-            accept(web_fd, (struct sockaddr *) &clientaddr, &clientlen);
-
-        char *p = web_recv(web_connfd, &clientaddr);
-        char *buffer = "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\n\r\n";
-        web_send(web_connfd, buffer);
-
-        if (p)
-            interpret_cmd(p);
-        free(p);
-        close(web_connfd);
     }
-    return result;
+    return 0;
 }
 
 bool finish_cmd()

linenoise.c

@@ -116,6 +116,7 @@
 #include <unistd.h>
 
 #include "linenoise.h"
+#include "web.h"
 
 #define LINENOISE_DEFAULT_HISTORY_MAX_LEN 100
 #define LINENOISE_MAX_LINE 4096
@@ -927,6 +928,11 @@ static int line_edit(int stdin_fd,
 
     if (write(l.ofd, prompt, l.plen) == -1)
         return -1;
+
+    int result = web_select(l.buf, l.ifd);
+    if (result != 0)
+        return result;
+
     while (1) {
         signed char c;
         int nread;
@@ -1362,4 +1368,4 @@ int line_history_load(const char *filename)
     }
     fclose(fp);
     return 0;
-}
+}

web.c

@@ -23,6 +23,8 @@
 #define TCP_CORK TCP_NOPUSH
 #endif
 
+int server_fd;
+
 typedef struct {
     int fd;            /* descriptor for this buf */
     int count;         /* unread byte in this buf */
@@ -153,6 +155,9 @@ int web_open(int port)
     /* Make it a listening socket ready to accept connection requests */
     if (listen(listenfd, LISTENQ) < 0)
         return -1;
+
+    server_fd = listenfd;
+
     return listenfd;
 }
 
@@ -228,3 +233,35 @@ char *web_recv(int fd, struct sockaddr_in *clientaddr)
 
     return ret;
 }
+
+int web_select(char *buf, int stdin_fd)
+{
+    fd_set listenset;
+
+    FD_ZERO(&listenset);
+    FD_SET(stdin_fd, &listenset);
+    int max_fd = stdin_fd;
+    if (server_fd > 0) {
+        FD_SET(server_fd, &listenset);
+        max_fd = max_fd > server_fd ? max_fd : server_fd;
+    }
+    int result = select(max_fd + 1, &listenset, NULL, NULL, NULL);
+    if (result < 0)
+        return -1;
+
+    if (server_fd > 0 && FD_ISSET(server_fd, &listenset)) {
+        FD_CLR(server_fd, &listenset);
+        struct sockaddr_in clientaddr;
+        socklen_t clientlen = sizeof(clientaddr);
+        int web_connfd =
+            accept(server_fd, (struct sockaddr *) &clientaddr, &clientlen);
+
+        char *p = web_recv(web_connfd, &clientaddr);
+        char *buffer = "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\n\r\n";
+        web_send(web_connfd, buffer);
+        strncpy(buf, p, strlen(p) + 1);
+        free(p);
+        close(web_connfd);
+    }
+    return strlen(buf);
+}

web.h

@@ -9,4 +9,6 @@ char *web_recv(int fd, struct sockaddr_in *clientaddr);
 
 void web_send(int out_fd, char *buffer);
 
+int web_select(char *buf, int stdin_fd);
+
 #endif