Introduce a redisFD type

The redisFD type should be equal to the system native socket file
desciptor type (for POSIX, this is a plain int).

We also introduce the REDIS_INVALID_FD value, which maps to -1 on POSIX
systems.

hiredis.c

@@ -620,9 +620,9 @@ void redisFree(redisContext *c) {
     free(c);
 }
 
-int redisFreeKeepFd(redisContext *c) {
-    int fd = c->fd;
-    c->fd = -1;
+redisFD redisFreeKeepFd(redisContext *c) {
+    redisFD fd = c->fd;
+    c->fd = REDIS_INVALID_FD;
     redisFree(c);
     return fd;
 }
@@ -746,7 +746,7 @@ redisContext *redisConnectUnixNonBlock(const char *path) {
     return redisConnectWithOptions(&options);
 }
 
-redisContext *redisConnectFd(int fd) {
+redisContext *redisConnectFd(redisFD fd) {
     redisOptions options = {0};
     options.type = REDIS_CONN_USERFD;
     options.endpoint.fd = fd;

hiredis.h

@@ -133,6 +133,9 @@ struct redisSsl;
  */
 #define REDIS_OPT_NOAUTOFREE 0x04
 
+typedef int redisFD;
+#define REDIS_INVALID_FD -1
+
 typedef struct {
     /*
      * the type of connection to use. This also indicates which
@@ -155,7 +158,7 @@ typedef struct {
         /**
          * use this field to have hiredis operate an already-open
          * file descriptor */
-        int fd;
+        redisFD fd;
     } endpoint;
 } redisOptions;
 
@@ -175,7 +178,7 @@ typedef struct {
 typedef struct redisContext {
     int err; /* Error flags, 0 when there is no error */
     char errstr[128]; /* String representation of error when applicable */
-    int fd;
+    redisFD fd;
     int flags;
     char *obuf; /* Write buffer */
     redisReader *reader; /* Protocol reader */
@@ -212,7 +215,7 @@ redisContext *redisConnectBindNonBlockWithReuse(const char *ip, int port,
 redisContext *redisConnectUnix(const char *path);
 redisContext *redisConnectUnixWithTimeout(const char *path, const struct timeval tv);
 redisContext *redisConnectUnixNonBlock(const char *path);
-redisContext *redisConnectFd(int fd);
+redisContext *redisConnectFd(redisFD fd);
 
 /**
  * Secure the connection using SSL. This should be done before any command is
@@ -235,7 +238,7 @@ int redisReconnect(redisContext *c);
 int redisSetTimeout(redisContext *c, const struct timeval tv);
 int redisEnableKeepAlive(redisContext *c);
 void redisFree(redisContext *c);
-int redisFreeKeepFd(redisContext *c);
+redisFD redisFreeKeepFd(redisContext *c);
 int redisBufferRead(redisContext *c);
 int redisBufferWrite(redisContext *c, int *done);
 

net.c

@@ -58,9 +58,9 @@
 void __redisSetError(redisContext *c, int type, const char *str);
 
 void redisNetClose(redisContext *c) {
-    if (c && c->fd >= 0) {
+    if (c && c->fd != REDIS_INVALID_FD) {
         close(c->fd);
-        c->fd = -1;
+        c->fd = REDIS_INVALID_FD;
     }
 }
 
@@ -117,8 +117,8 @@ static int redisSetReuseAddr(redisContext *c) {
 }
 
 static int redisCreateSocket(redisContext *c, int type) {
-    int s;
-    if ((s = socket(type, SOCK_STREAM, 0)) == -1) {
+    redisFD s;
+    if ((s = socket(type, SOCK_STREAM, 0)) == REDIS_INVALID_FD) {
         __redisSetErrorFromErrno(c,REDIS_ERR_IO,NULL);
         return REDIS_ERR;
     }
@@ -158,7 +158,7 @@ static int redisSetBlocking(redisContext *c, int blocking) {
 
 int redisKeepAlive(redisContext *c, int interval) {
     int val = 1;
-    int fd = c->fd;
+    redisFD fd = c->fd;
 
     if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &val, sizeof(val)) == -1){
         __redisSetError(c,REDIS_ERR_OTHER,strerror(errno));
@@ -322,7 +322,8 @@ int redisContextSetTimeout(redisContext *c, const struct timeval tv) {
 static int _redisContextConnectTcp(redisContext *c, const char *addr, int port,
                                    const struct timeval *timeout,
                                    const char *source_addr) {
-    int s, rv, n;
+    redisFD s;
+    int rv, n;
     char _port[6];  /* strlen("65535"); */
     struct addrinfo hints, *servinfo, *bservinfo, *p, *b;
     int blocking = (c->flags & REDIS_BLOCK);
@@ -391,7 +392,7 @@ static int _redisContextConnectTcp(redisContext *c, const char *addr, int port,
     }
     for (p = servinfo; p != NULL; p = p->ai_next) {
 addrretry:
-        if ((s = socket(p->ai_family,p->ai_socktype,p->ai_protocol)) == -1)
+        if ((s = socket(p->ai_family,p->ai_socktype,p->ai_protocol)) == REDIS_INVALID_FD)
             continue;
 
         c->fd = s;