Merged PR 698510: Interpose dup calls for fd_table correctness

`dup` returns a new file descriptor, so we should treat it as an `open` and reset the fd table. `dup2` and `dup3` silently close file descriptors, so we have to invalidate the entries for those fds.

Author: marcelolynch

Public/Src/Sandbox/Linux/bxl_observer.hpp

@@ -496,10 +496,11 @@ class BxlObserver final
     GEN_FN_DEF(ssize_t, sendfile64, int out_fd, int in_fd, off_t *offset, size_t count);
     GEN_FN_DEF(ssize_t, copy_file_range, int fd_in, loff_t *off_in, int fd_out, loff_t *off_out, size_t len, unsigned int flags);
     GEN_FN_DEF(int, name_to_handle_at, int dirfd, const char *pathname, struct file_handle *handle, int *mount_id, int flags);
-
-    /* ============ don't need to be interposed ======================= */
     GEN_FN_DEF(int, dup, int oldfd);
     GEN_FN_DEF(int, dup2, int oldfd, int newfd);
+    GEN_FN_DEF(int, dup3, int oldfd, int newfd, int flags);
+
+    /* ============ don't need to be interposed ======================= */
     GEN_FN_DEF(int, close, int fd);
     GEN_FN_DEF(int, fclose, FILE *stream);
     GEN_FN_DEF(int, statfs, const char *, struct statfs *buf);

Public/Src/Sandbox/Linux/detours.cpp

@@ -804,6 +804,32 @@ INTERPOSE(int, fclose, FILE *f) ({
     return bxl->fwd_fclose(f).restore();
 })
 
+INTERPOSE(int, dup, int fd) ({ 
+    return ret_fd(bxl->real_dup(fd), bxl);    
+    // Sometimes useful (for debugging) to interpose without access checking:
+    // return bxl->fwd_dup(fd).restore();     
+})
+
+INTERPOSE(int, dup2, int oldfd, int newfd)({
+    // If the file descriptor newfd was previously open, it is closed
+    // before being reused; the close is performed silently, so we should reset the fd table.
+    bxl->reset_fd_table_entry(newfd);
+
+    return bxl->real_dup2(oldfd, newfd); 
+    // Sometimes useful (for debugging) to interpose without access checking:
+    // return bxl->fwd_dup2(oldfd, newfd).restore();  
+})
+
+INTERPOSE(int, dup3, int oldfd, int newfd, int flags)({
+    // If the file descriptor newfd was previously open, it is closed
+    // before being reused; the close is performed silently, so we should reset the fd table.
+    bxl->reset_fd_table_entry(newfd);
+
+    return bxl->real_dup3(oldfd, newfd, flags); 
+    // Sometimes useful (for debugging) to interpose without access checking:
+    //return bxl->fwd_dup3(oldfd, newfd).restore();  
+})
+
 static void report_exit(int exitCode, void *args)
 {
     BxlObserver::GetInstance()->report_access("on_exit", ES_EVENT_TYPE_NOTIFY_EXIT, std::string(""), std::string(""));
@@ -828,13 +854,6 @@ int main(int argc, char **argv)
     printf("Path: %s\n", inst->GetReportsPath());
 }
 
-/* ============ Sometimes useful (for debugging) to interpose without access checking
-
-INTERPOSE(int, dup, int fd)               ({ return bxl->fwd_dup(fd).restore(); })
-INTERPOSE(int, dup2, int oldfd, int newfd)({ return bxl->fwd_dup2(oldfd, newfd).restore(); })
-
-=================================================================== */
-
 /* ============ don't need to be interposed =======================
 
 INTERPOSE(int, statfs, const char *pathname, struct statfs *buf)({