[clang] [clang][analyzer] Model more getline/getdelim pre and postconditions (PR #83027)

[Balázs Kéri via cfe-commits]

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@@ -376,3 +377,75 @@ void fflush_on_open_failed_stream(void) {
   }
   fclose(F);
 }
+
+void getline_null_file() {
+  char *buffer = NULL;
+  size_t n = 0;
+  getline(&buffer, &n, NULL); // expected-warning {{Stream pointer might be NULL}}
+}
+
+void getdelim_null_file() {
+  char *buffer = NULL;
+  size_t n = 0;
+  getdelim(&buffer, &n, '\n', NULL); // expected-warning {{Stream pointer might be NULL}}
+}
+
+void getline_buffer_on_error() {
+  FILE *file = fopen("file.txt", "r");
+  if (file == NULL) {
+    return;
+  }
+
+  char *line = NULL;
+  size_t len = 0;
+  if (getline(&line, &len, file) == -1) {
+    if (line[0] == '\0') {} // expected-warning {{The left operand of '==' is a garbage value}}
+  } else {
+    if (line[0] == '\0') {} // no warning
+  }
+
+  free(line);
+  fclose(file);
+}
+
+void getline_ret_value() {
+  FILE *file = fopen("file.txt", "r");
+  if (file == NULL) {
+    return;
+  }
+
+  size_t n = 0;
+  char *buffer = NULL;
+  ssize_t r = getline(&buffer, &n, file);
+
+  if (r > -1) {
+    // The return value does *not* include the terminating null byte.
+    // The buffer must be large enough to include it.
+    clang_analyzer_eval(n > r); // expected-warning{{TRUE}}
+    clang_analyzer_eval(buffer != NULL);  // expected-warning{{TRUE}}
+  }
+
+  fclose(file);
+  free(buffer);
+}
+
+
+void getline_buffer_size_negative() {
+  FILE *file = fopen("file.txt", "r");
+  if (file == NULL) {
+    return;
+  }
+
+  size_t n = -1;
+  clang_analyzer_eval((ssize_t)n >= 0); // expected-warning{{FALSE}}
+  char *buffer = NULL;
+  ssize_t r = getline(&buffer, &n, file);
+
+  if (r > -1) {
+    clang_analyzer_eval((ssize_t)n > r); // expected-warning{{TRUE}}
+	clang_analyzer_eval(buffer != NULL); // expected-warning{{TRUE}}
----------------
balazske wrote:

This looks like an indentation problem.

https://github.com/llvm/llvm-project/pull/83027