libbpf-tools: fix non-C89-compliant for loop variable declarations

Fix all the found instances of declaring loop variable inside for() construct,
which is not supported in C89 standard, which is what libbpf-tools are trying
to adhere to, both in user-space and BPF source code. It actually causes
compilation errors on some versions of GCC, as reported by customers in
private conversations.

Signed-off-by: Andrii Nakryiko <[email protected]>

libbpf-tools/errno_helpers.c

@@ -159,7 +159,7 @@ static int errno_by_name_x86_64(const char *errno_name)
 /* Try to find the errno number using the errno(1) program */
 static int errno_by_name_dynamic(const char *errno_name)
 {
- int len = strlen(errno_name);
+ int i, len = strlen(errno_name);
  int err, number = -1;
  char buf[128];
  char cmd[64];
@@ -168,7 +168,7 @@ static int errno_by_name_dynamic(const char *errno_name)
  FILE *f;
 
  /* sanity check to not call popen with random input */
- for (int i = 0; i < len; i++) {
+ for (i = 0; i < len; i++) {
  if (errno_name[i] < 'A' || errno_name[i] > 'Z') {
  warn("errno_name contains invalid char 0x%02x: %s\n",
  errno_name[i], errno_name);

libbpf-tools/execsnoop.bpf.c

@@ -38,6 +38,7 @@ int tracepoint__syscalls__sys_enter_execve(struct trace_event_raw_sys_enter* ctx
  const char **args = (const char **)(ctx->args[1]);
  const char *argp;
  uid_t uid = (u32)bpf_get_current_uid_gid();
+ int i;
 
  if (valid_uid(targ_uid) && targ_uid != uid)
  return 0;
@@ -71,7 +72,7 @@ int tracepoint__syscalls__sys_enter_execve(struct trace_event_raw_sys_enter* ctx
 
  event->args_count++;
  #pragma unroll
- for (int i = 1; i < TOTAL_MAX_ARGS && i < max_args; i++) {
+ for (i = 1; i < TOTAL_MAX_ARGS && i < max_args; i++) {
  bpf_probe_read_user(&argp, sizeof(argp), &args[i]);
  if (!argp)
  return 0;

libbpf-tools/execsnoop.c

@@ -174,13 +174,14 @@ static void inline quoted_symbol(char c) {
 
 static void print_args(const struct event *e, bool quote)
 {
- int args_counter = 0;
+ int i, args_counter = 0;
 
  if (env.quote)
  putchar('"');
 
- for (int i = 0; i < e->args_size && args_counter < e->args_count; i++) {
+ for (i = 0; i < e->args_size && args_counter < e->args_count; i++) {
  char c = e->args[i];
+
  if (env.quote) {
  if (c == '\0') {
  args_counter++;

libbpf-tools/funclatency.c

@@ -274,7 +274,7 @@ int main(int argc, char **argv)
  .doc = program_doc,
  };
  struct funclatency_bpf *obj;
- int err;
+ int i, err;
  struct tm *tm;
  char ts[32];
  time_t t;
@@ -312,7 +312,7 @@ int main(int argc, char **argv)
 
  printf("Tracing %s. Hit Ctrl-C to exit\n", env.funcname);
 
- for (int i = 0; i < env.iterations && !exiting; i++) {
+ for (i = 0; i < env.iterations && !exiting; i++) {
  sleep(env.interval);
 
  printf("\n");

libbpf-tools/map_helpers.c

@@ -17,7 +17,7 @@ dump_hash_iter(int map_fd, void *keys, __u32 key_size,
 {
  __u8 key[key_size], next_key[key_size];
  __u32 n = 0;
- int err;
+ int i, err;
 
  /* First get keys */
  __builtin_memcpy(key, invalid_key, key_size);
@@ -34,7 +34,7 @@ dump_hash_iter(int map_fd, void *keys, __u32 key_size,
  }
 
  /* Now read values */
- for (int i = 0; i < n; i++) {
+ for (i = 0; i < n; i++) {
  err = bpf_map_lookup_elem(map_fd, keys + key_size * i,
  values + value_size * i);
  if (err)

libbpf-tools/syscall_helpers.c

@@ -116,7 +116,9 @@ void init_syscall_names(void)
 
 void free_syscall_names(void)
 {
- for (size_t i = 0; i < syscall_names_size; i++)
+ size_t i;
+
+ for (i = 0; i < syscall_names_size; i++)
  free((void *) syscall_names[i]);
  free(syscall_names);
 }
@@ -507,7 +509,7 @@ void syscall_name(unsigned n, char *buf, size_t size)
 int list_syscalls(void)
 {
  const char **list = syscall_names;
- size_t size = syscall_names_size;
+ size_t i, size = syscall_names_size;
 
 #ifdef __x86_64__
  if (!size) {
@@ -516,7 +518,7 @@ int list_syscalls(void)
  }
 #endif
 
- for (size_t i = 0; i < size; i++) {
+ for (i = 0; i < size; i++) {
  if (list[i])
  printf("%3zd: %s\n", i, list[i]);
  }

libbpf-tools/syscount.c

@@ -149,9 +149,10 @@ static void print_latency(struct data_ext_t *vals, size_t count)
 {
  double div = env.milliseconds ? 1000000.0 : 1000.0;
  char buf[2 * TASK_COMM_LEN];
+ int i;
 
  print_latency_header();
- for (int i = 0; i < count && i < env.top; i++)
+ for (i = 0; i < count && i < env.top; i++)
  printf("%-22s %8llu %16.3lf\n",
  agg_col(&vals[i], buf, sizeof(buf)),
  vals[i].count, vals[i].total_ns / div);
@@ -161,9 +162,10 @@ static void print_latency(struct data_ext_t *vals, size_t count)
 static void print_count(struct data_ext_t *vals, size_t count)
 {
  char buf[2 * TASK_COMM_LEN];
+ int i;
 
  print_count_header();
- for (int i = 0; i < count && i < env.top; i++)
+ for (i = 0; i < count && i < env.top; i++)
  printf("%-22s %8llu\n",
  agg_col(&vals[i], buf, sizeof(buf)), vals[i].count);
  printf("\n");
@@ -186,7 +188,7 @@ static bool read_vals_batch(int fd, struct data_ext_t *vals, __u32 *count)
 {
  struct data_t orig_vals[*count];
  void *in = NULL, *out;
- __u32 n, n_read = 0;
+ __u32 i, n, n_read = 0;
  __u32 keys[*count];
  int err = 0;
 
@@ -206,7 +208,7 @@ static bool read_vals_batch(int fd, struct data_ext_t *vals, __u32 *count)
  in = out;
  }
 
- for (__u32 i = 0; i < n_read; i++) {
+ for (i = 0; i < n_read; i++) {
  vals[i].count = orig_vals[i].count;
  vals[i].total_ns = orig_vals[i].total_ns;
  vals[i].key = keys[i];
@@ -223,7 +225,7 @@ static bool read_vals(int fd, struct data_ext_t *vals, __u32 *count)
  struct data_t val;
  __u32 key = -1;
  __u32 next_key;
- int i = 0;
+ int i = 0, j;
  int err;
 
  if (batch_map_ops) {
@@ -250,7 +252,7 @@ static bool read_vals(int fd, struct data_ext_t *vals, __u32 *count)
  key = keys[i++] = next_key;
  }
 
- for (int j = 0; j < i; j++) {
+ for (j = 0; j < i; j++) {
  err = bpf_map_lookup_elem(fd, &keys[j], &val);
  if (err && errno != ENOENT) {
  warn("failed to lookup element: %s\n", strerror(errno));
@@ -267,7 +269,7 @@ static bool read_vals(int fd, struct data_ext_t *vals, __u32 *count)
  * will be fixed in future by using bpf_map_lookup_and_delete_batch,
  * but this function is too fresh to use it in bcc. */
 
- for (int j = 0; j < i; j++) {
+ for (j = 0; j < i; j++) {
  err = bpf_map_delete_elem(fd, &keys[j]);
  if (err) {
  warn("failed to delete element: %s\n", strerror(errno));

libbpf-tools/tcpconnect.bpf.c

@@ -53,10 +53,12 @@ struct {
 
 static __always_inline bool filter_port(__u16 port)
 {
+ int i;
+
  if (filter_ports_len == 0)
  return false;
 
- for (int i = 0; i < filter_ports_len; i++) {
+ for (i = 0; i < filter_ports_len; i++) {
  if (port == filter_ports[i])
  return false;
  }

libbpf-tools/tcpconnect.c

@@ -203,7 +203,7 @@ static void print_count_ipv4(int map_fd)
  static __u64 counts[MAX_ENTRIES];
  char s[INET_ADDRSTRLEN];
  char d[INET_ADDRSTRLEN];
- __u32 n = MAX_ENTRIES;
+ __u32 i, n = MAX_ENTRIES;
  struct in_addr src;
  struct in_addr dst;
 
@@ -212,7 +212,7 @@ static void print_count_ipv4(int map_fd)
  return;
  }
 
- for (__u32 i = 0; i < n; i++) {
+ for (i = 0; i < n; i++) {
  src.s_addr = keys[i].saddr;
  dst.s_addr = keys[i].daddr;
 
@@ -232,7 +232,7 @@ static void print_count_ipv6(int map_fd)
  static __u64 counts[MAX_ENTRIES];
  char s[INET6_ADDRSTRLEN];
  char d[INET6_ADDRSTRLEN];
- __u32 n = MAX_ENTRIES;
+ __u32 i, n = MAX_ENTRIES;
  struct in6_addr src;
  struct in6_addr dst;
 
@@ -241,7 +241,7 @@ static void print_count_ipv6(int map_fd)
  return;
  }
 
- for (__u32 i = 0; i < n; i++) {
+ for (i = 0; i < n; i++) {
  memcpy(src.s6_addr, keys[i].saddr, sizeof(src.s6_addr));
  memcpy(dst.s6_addr, keys[i].daddr, sizeof(src.s6_addr));
 
@@ -357,7 +357,7 @@ int main(int argc, char **argv)
  .args_doc = NULL,
  };
  struct tcpconnect_bpf *obj;
- int err;
+ int i, err;
 
  err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
  if (err)
@@ -385,7 +385,7 @@ int main(int argc, char **argv)
  obj->rodata->filter_uid = env.uid;
  if (env.nports > 0) {
  obj->rodata->filter_ports_len = env.nports;
- for (int i = 0; i < env.nports; i++) {
+ for (i = 0; i < env.nports; i++) {
  obj->rodata->filter_ports[i] = htons(env.ports[i]);
  }
  }

libbpf-tools/uprobe_helpers.c

@@ -199,7 +199,7 @@ static void close_elf(Elf *e, int fd_close)
 off_t get_elf_func_offset(const char *path, const char *func)
 {
  off_t ret = -1;
- int fd = -1;
+ int i, fd = -1;
  Elf *e;
  Elf_Scn *scn;
  Elf_Data *data;
@@ -221,7 +221,7 @@ off_t get_elf_func_offset(const char *path, const char *func)
  continue;
  data = NULL;
  while ((data = elf_getdata(scn, data))) {
- for (int i = 0; gelf_getsym(data, i, sym); i++) {
+ for (i = 0; gelf_getsym(data, i, sym); i++) {
  n = elf_strptr(e, shdr->sh_link, sym->st_name);
  if (!n)
  continue;

libbpf-tools/vfsstat.c

@@ -109,8 +109,10 @@ static const char *stat_types_names[] = {
 
 static void print_header(void)
 {
+ int i;
+
  printf("%-8s ", "TIME");
- for (int i = 0; i < S_MAXSTAT; i++)
+ for (i = 0; i < S_MAXSTAT; i++)
  printf(" %6s/s", stat_types_names[i]);
  printf("\n");
 }
@@ -119,9 +121,10 @@ static void print_and_reset_stats(__u64 stats[S_MAXSTAT])
 {
  char s[16];
  __u64 val;
+ int i;
 
  printf("%-8s: ", strftime_now(s, sizeof(s), "%H:%M:%S"));
- for (int i = 0; i < S_MAXSTAT; i++) {
+ for (i = 0; i < S_MAXSTAT; i++) {
  val = __atomic_exchange_n(&stats[i], 0, __ATOMIC_RELAXED);
  printf(" %8llu", val / env.interval);
  }