libreprl: rename stdout and stderr fields (NFC) (googleprojectzero#273)

This renames the `stdout` and `stderr` fields to `child_stdout` and
`child_strerr` respectively.  `stdout` and `stderr` are reserved by the C
standard library, which may define them using a macro.  In such a case, the
re-use of the identifier literal as a field will be improperly expanded by the
CPP.  This actually occurs in practive with ucrt, which uses macros for the
indirection of the iostreams.  This makes the code more resilient to different
libc implementations.

Author: compnerd

Sources/libreprl/libreprl.c

@@ -94,8 +94,8 @@ struct reprl_context {
     struct data_channel* data_out;
 
     // Optional data channel for the child's stdout and stderr.
-    struct data_channel* stdout;
-    struct data_channel* stderr;
+    struct data_channel* child_stdout;
+    struct data_channel* child_stderr;
 
     // PID of the child process. Will be zero if no child process is currently running.
     int pid;
@@ -176,8 +176,8 @@ static int reprl_spawn_child(struct reprl_context* ctx)
     // This is also a good time to ensure the data channel backing files don't grow too large.
     ftruncate(ctx->data_in->fd, REPRL_MAX_DATA_SIZE);
     ftruncate(ctx->data_out->fd, REPRL_MAX_DATA_SIZE);
-    if (ctx->stdout) ftruncate(ctx->stdout->fd, REPRL_MAX_DATA_SIZE);
-    if (ctx->stderr) ftruncate(ctx->stderr->fd, REPRL_MAX_DATA_SIZE);
+    if (ctx->child_stdout) ftruncate(ctx->child_stdout->fd, REPRL_MAX_DATA_SIZE);
+    if (ctx->child_stderr) ftruncate(ctx->child_stderr->fd, REPRL_MAX_DATA_SIZE);
 
     int crpipe[2] = { 0, 0 };          // control pipe child -> reprl
     int cwpipe[2] = { 0, 0 };          // control pipe reprl -> child
@@ -225,9 +225,9 @@ static int reprl_spawn_child(struct reprl_context* ctx)
 
         int devnull = open("/dev/null", O_RDWR);
         dup2(devnull, 0);
-        if (ctx->stdout) dup2(ctx->stdout->fd, 1);
+        if (ctx->child_stdout) dup2(ctx->child_stdout->fd, 1);
         else dup2(devnull, 1);
-        if (ctx->stderr) dup2(ctx->stderr->fd, 2);
+        if (ctx->child_stderr) dup2(ctx->child_stderr->fd, 2);
         else dup2(devnull, 2);
         close(devnull);
 
@@ -307,12 +307,12 @@ int reprl_initialize_context(struct reprl_context* ctx, const char** argv, const
     ctx->data_in = reprl_create_data_channel(ctx);
     ctx->data_out = reprl_create_data_channel(ctx);
     if (capture_stdout) {
-        ctx->stdout = reprl_create_data_channel(ctx);
+        ctx->child_stdout = reprl_create_data_channel(ctx);
     }
     if (capture_stderr) {
-        ctx->stderr = reprl_create_data_channel(ctx);
+        ctx->child_stderr = reprl_create_data_channel(ctx);
     }
-    if (!ctx->data_in || !ctx->data_out || (capture_stdout && !ctx->stdout) || (capture_stderr && !ctx->stderr)) {
+    if (!ctx->data_in || !ctx->data_out || (capture_stdout && !ctx->child_stdout) || (capture_stderr && !ctx->child_stderr)) {
         // Proper error message will have been set by reprl_create_data_channel
         return -1;
     }
@@ -330,8 +330,8 @@ void reprl_destroy_context(struct reprl_context* ctx)
 
     reprl_destroy_data_channel(ctx, ctx->data_in);
     reprl_destroy_data_channel(ctx, ctx->data_out);
-    reprl_destroy_data_channel(ctx, ctx->stdout);
-    reprl_destroy_data_channel(ctx, ctx->stderr);
+    reprl_destroy_data_channel(ctx, ctx->child_stdout);
+    reprl_destroy_data_channel(ctx, ctx->child_stderr);
 
     free(ctx->last_error);
     free(ctx);
@@ -354,11 +354,11 @@ int reprl_execute(struct reprl_context* ctx, const char* script, uint64_t script
     // Reset file position so the child can simply read(2) and write(2) to these fds.
     lseek(ctx->data_out->fd, 0, SEEK_SET);
     lseek(ctx->data_in->fd, 0, SEEK_SET);
-    if (ctx->stdout) {
-        lseek(ctx->stdout->fd, 0, SEEK_SET);
+    if (ctx->child_stdout) {
+        lseek(ctx->child_stdout->fd, 0, SEEK_SET);
     }
-    if (ctx->stderr) {
-        lseek(ctx->stderr->fd, 0, SEEK_SET);
+    if (ctx->child_stderr) {
+        lseek(ctx->child_stderr->fd, 0, SEEK_SET);
     }
 
     // Spawn a new instance if necessary.
@@ -490,12 +490,12 @@ const char* reprl_fetch_fuzzout(struct reprl_context* ctx)
 
 const char* reprl_fetch_stdout(struct reprl_context* ctx)
 {
-    return fetch_data_channel_content(ctx->stdout);
+    return fetch_data_channel_content(ctx->child_stdout);
 }
 
 const char* reprl_fetch_stderr(struct reprl_context* ctx)
 {
-    return fetch_data_channel_content(ctx->stderr);
+    return fetch_data_channel_content(ctx->child_stderr);
 }
 
 const char* reprl_get_last_error(struct reprl_context* ctx)