Various paginate improvements (#1148)

* start on improving __paginate

* make __paginate more robust

* add __paginate_file

* cleanup __paginate unlinking

libc/runtime/runtime.h

@@ -103,6 +103,7 @@ int verynice(void);
 void __warn_if_powersave(void);
 void _Exit1(int) libcesque wontreturn;
 void __paginate(int, const char *);
+void __paginate_file(int, const char *);
 /* memory management */
 void _weakfree(void *);
 void *_mapanon(size_t) attributeallocsize((1)) mallocesque;

libc/x/paginate.c

@@ -17,28 +17,37 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
+#include "libc/calls/syscall_support-nt.internal.h"
+#include "libc/dce.h"
 #include "libc/intrin/safemacros.internal.h"
 #include "libc/limits.h"
+#include "libc/mem/gc.h"
 #include "libc/runtime/runtime.h"
 #include "libc/str/str.h"
+#include "libc/sysv/consts/o.h"
 #include "libc/temp.h"
+#include "libc/x/x.h"
 
-/**
+static char *get_pagerpath(char *pathbuf, size_t pathbufsz) {
- * Displays wall of text in terminal with pagination.
+  char *pagerpath;
- */
-void __paginate(int fd, const char *s) {
-  int tfd, pid;
-  char *args[3] = {0};
-  char tmppath[] = "/tmp/paginate.XXXXXX";
-  char progpath[PATH_MAX];
   if (strcmp(nulltoempty(getenv("TERM")), "dumb") && isatty(0) && isatty(1) &&
-      ((args[0] = commandv("less", progpath, sizeof(progpath))) ||
+      ((pagerpath = commandv("less", pathbuf, pathbufsz)) ||
-       (args[0] = commandv("more", progpath, sizeof(progpath))) ||
+       (pagerpath = commandv("more", pathbuf, pathbufsz)) ||
-       (args[0] = commandv("more.exe", progpath, sizeof(progpath))))) {
+       (pagerpath = commandv("more.exe", pathbuf, pathbufsz)) ||
-    if ((tfd = mkstemp(tmppath)) != -1) {
+       (pagerpath = commandv("more.com", pathbuf, pathbufsz)))) {
-      write(tfd, s, strlen(s));
+    return pagerpath;
-      close(tfd);
+  }
-      args[1] = tmppath;
+  return 0;
+}
+
+static bool run_pager(char *args[hasatleast 3]) {
+  char16_t widepath[PATH_MAX];
+  int n, pid;
+  if (IsWindows() && !strcasecmp(args[0], "/C/Windows/System32/more.com") &&
+      (((n = __mkntpath(args[1], widepath)) == -1) ||
+       !(args[1] = gc(utf16to8(widepath, n, 0))))) {
+    return false;
+  }
   if ((pid = fork()) != -1) {
     putenv("LC_ALL=C.UTF-8");
     putenv("LESSCHARSET=utf-8");
@@ -48,11 +57,53 @@ void __paginate(int fd, const char *s) {
       _Exit(127);
     }
     waitpid(pid, 0, 0);
+    return true;
+  }
+  return false;
+}
+
+/**
+ * Displays wall of text in terminal with pagination.
+ */
+void __paginate(int fd, const char *s) {
+  int tfd;
+  char *args[3] = {0};
+  char tmppath[] = "/tmp/paginate.XXXXXX";
+  char progpath[PATH_MAX];
+  bool done;
+  if ((args[0] = get_pagerpath(progpath, sizeof(progpath)))) {
+    if ((tfd = mkstemp(tmppath)) != -1) {
+      write(tfd, s, strlen(s));
+      close(tfd);
+      args[1] = tmppath;
+      done = run_pager(args);
       unlink(tmppath);
+      if (done) {
         return;
       }
-      unlink(tmppath);
     }
   }
   write(fd, s, strlen(s));
 }
+
+/**
+ * Displays a file in terminal with pagination
+ */
+void __paginate_file(int fd, const char *path) {
+  char *args[3] = {0};
+  char progpath[PATH_MAX];
+  if ((args[0] = get_pagerpath(progpath, sizeof(progpath)))) {
+    args[1] = (char *)path;
+    if (run_pager(args)) {
+      return;
+    }
+  }
+  int sfd = open(path, O_RDONLY);
+  if (sfd != -1) {
+    ssize_t n;
+    while ((n = read(sfd, progpath, sizeof(progpath)) > 0)) {
+      write(fd, progpath, n);
+    }
+  }
+  close(sfd);
+}