selftests/bpf: improve error messages in veristat

Return error if preset parsing fails. Avoid proceeding with veristat run
if preset does not parse.
Before:
```
./veristat set_global_vars.bpf.o -G "arr[999999999999999999999] = 1"
Failed to parse value '999999999999999999999'
Processing 'set_global_vars.bpf.o'...
File                   Program           Verdict  Duration (us)  Insns  States  Program size  Jited size
---------------------  ----------------  -------  -------------  -----  ------  ------------  ----------
set_global_vars.bpf.o  test_set_globals  success             27     64       0            82           0
---------------------  ----------------  -------  -------------  -----  ------  ------------  ----------
Done. Processed 1 files, 0 programs. Skipped 1 files, 0 programs.
```
After:
```
./veristat set_global_vars.bpf.o -G "arr[999999999999999999999] = 1"
Failed to parse value '999999999999999999999'
Failed to parse global variable presets: arr[999999999999999999999] = 1
```

Improve error messages:
 * If preset struct member can't be found.
 * Array index out of bounds

Extract rtrim function.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250627144342.686896-1-mykyta.yatsenko5@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selftests/bpf/veristat.c
index 1e9f61f9fd0adc08cfc7773af5bfe57a54b53b66..09cfbd486f92dda3a08cebd03b0d59ba515c6100 100644 (file)
--- a/tools/testing/selftests/bpf/veristat.c
+++ b/tools/testing/selftests/bpf/veristat.c
@@ -890,6 +890,18 @@ static bool is_desc_sym(char c)
        return c == 'v' || c == 'V' || c == '.' || c == '!' || c == '_';
 }
 
+static char *rtrim(char *str)
+{
+       int i;
+
+       for (i = strlen(str) - 1; i > 0; --i) {
+               if (!isspace(str[i]))
+                       break;
+               str[i] = '\0';
+       }
+       return str;
+}
+
 static int parse_stat(const char *stat_name, struct stat_specs *specs)
 {
        int id;
@@ -1666,7 +1678,7 @@ static int append_preset_atom(struct var_preset *preset, char *value, bool is_in
 static int parse_var_atoms(const char *full_var, struct var_preset *preset)
 {
        char expr[256], var[256], *name, *saveptr;
-       int n, len, off;
+       int n, len, off, err;
 
        snprintf(expr, sizeof(expr), "%s", full_var);
        preset->atom_count = 0;
@@ -1677,7 +1689,9 @@ static int parse_var_atoms(const char *full_var, struct var_preset *preset)
                        fprintf(stderr, "Can't parse %s\n", name);
                        return -EINVAL;
                }
-               append_preset_atom(preset, var, false);
+               err = append_preset_atom(preset, var, false);
+               if (err)
+                       return err;
 
                /* parse optional array indexes */
                while (off < len) {
@@ -1685,7 +1699,9 @@ static int parse_var_atoms(const char *full_var, struct var_preset *preset)
                                fprintf(stderr, "Can't parse %s as index\n", name + off);
                                return -EINVAL;
                        }
-                       append_preset_atom(preset, var, true);
+                       err = append_preset_atom(preset, var, true);
+                       if (err)
+                               return err;
                        off += n;
                }
        }
@@ -1697,7 +1713,7 @@ static int append_var_preset(struct var_preset **presets, int *cnt, const char *
        void *tmp;
        struct var_preset *cur;
        char var[256], val[256];
-       int n, err, i;
+       int n, err;
 
        tmp = realloc(*presets, (*cnt + 1) * sizeof(**presets));
        if (!tmp)
@@ -1712,11 +1728,7 @@ static int append_var_preset(struct var_preset **presets, int *cnt, const char *
                return -EINVAL;
        }
        /* Remove trailing spaces from var, as scanf may add those */
-       for (i = strlen(var) - 1; i > 0; --i) {
-               if (!isspace(var[i]))
-                       break;
-               var[i] = '\0';
-       }
+       rtrim(var);
 
        err = parse_rvalue(val, &cur->value);
        if (err)
@@ -1869,7 +1881,7 @@ static int adjust_var_secinfo_array(struct btf *btf, int tid, struct field_acces
        if (err)
                return err;
        if (idx < 0 || idx >= barr->nelems) {
-               fprintf(stderr, "Array index %lld is out of bounds [0, %u]: %s\n",
+               fprintf(stderr, "Array index %lld is out of bounds [0, %u): %s\n",
                        idx, barr->nelems, array_name);
                return -EINVAL;
        }
@@ -1928,7 +1940,7 @@ static int adjust_var_secinfo_member(const struct btf *btf,
                }
        }
 
-       return -EINVAL;
+       return -ESRCH;
 }
 
 static int adjust_var_secinfo(struct btf *btf, const struct btf_type *t,
@@ -1955,6 +1967,8 @@ static int adjust_var_secinfo(struct btf *btf, const struct btf_type *t,
                        break;
                case FIELD_NAME:
                        err = adjust_var_secinfo_member(btf, base_type, 0, atom->name, sinfo);
+                       if (err == -ESRCH)
+                               fprintf(stderr, "Can't find '%s'\n", atom->name);
                        prev_name = atom->name;
                        break;
                default: