Enable printf, cat, system to have more args

CHANGELOG.md

@@ -48,6 +48,8 @@ and this project adheres to
   - [#1377](https://github.com/iovisor/bpftrace/pull/1377)
 - Add support for non-map print()
   - [#1381](https://github.com/iovisor/bpftrace/pull/1381)
+- Enable `printf`, `cat` and `system` to have more than 7 arguments
+  - [#1404](https://github.com/iovisor/bpftrace/pull/1404)
 
 #### Changed
 

src/ast/semantic_analyser.cpp

@@ -766,7 +766,7 @@ void SemanticAnalyser::visit(Call &call)
   else if (call.func == "printf" || call.func == "system" || call.func == "cat")
   {
     check_assignment(call, false, false, false);
-    if (check_varargs(call, 1, 7))
+    if (check_varargs(call, 1, std::numeric_limits<int>::max()))
     {
       check_arg(call, Type::string, 0, true);
       if (is_final_pass())

src/bpftrace.cpp

@@ -49,52 +49,46 @@ DebugLevel bt_debug = DebugLevel::kNone;
 bool bt_verbose = false;
 volatile sig_atomic_t BPFtrace::exitsig_recv = false;
 
-int format(char * s, size_t n, const char * fmt, std::vector<std::unique_ptr<IPrintable>> &args) {
+int format(char *s,
+           size_t n,
+           std::string fmt,
+           std::vector<std::unique_ptr<IPrintable>> &args)
+{
   // Args have been made safe for printing by now, so replace nonstandard format
   // specifiers with %s
-  std::string str = std::string(fmt);
   size_t start_pos = 0;
-  while ((start_pos = str.find("%r", start_pos)) != std::string::npos)
+  while ((start_pos = fmt.find("%r", start_pos)) != std::string::npos)
   {
-    str.replace(start_pos, 2, "%s");
+    fmt.replace(start_pos, 2, "%s");
     start_pos += 2;
   }
-  fmt = str.c_str();
 
-  int ret = -1;
-  switch(args.size()) {
-    case 0:
-      ret = snprintf(s, n, "%s", fmt);
-      break;
-    case 1:
-      ret = snprintf(s, n, fmt, args.at(0)->value());
-      break;
-    case 2:
-      ret = snprintf(s, n, fmt, args.at(0)->value(), args.at(1)->value());
-      break;
-    case 3:
-      ret = snprintf(s, n, fmt, args.at(0)->value(), args.at(1)->value(), args.at(2)->value());
-      break;
-    case 4:
-      ret = snprintf(s, n, fmt, args.at(0)->value(), args.at(1)->value(), args.at(2)->value(), args.at(3)->value());
-      break;
-    case 5:
-      ret = snprintf(s, n, fmt, args.at(0)->value(), args.at(1)->value(), args.at(2)->value(),
-        args.at(3)->value(), args.at(4)->value());
-      break;
-    case 6:
-      ret = snprintf(s, n, fmt, args.at(0)->value(), args.at(1)->value(), args.at(2)->value(),
-        args.at(3)->value(), args.at(4)->value(), args.at(5)->value());
-      break;
-    default:
-      std::cerr << "format() can only take up to 7 arguments (" << args.size() << ") provided" << std::endl;
+  const std::regex re("%-?[0-9]*(\\.[0-9]+)?[a-zA-Z]+");
+  auto tokens_begin = std::sregex_iterator(fmt.begin(), fmt.end(), re);
+  auto tokens_end = std::sregex_iterator();
+
+  int text_pos = 0;
+  int i = 0;
+  std::string str;
+  while (tokens_begin != tokens_end)
+  {
+    int match_start = tokens_begin->position();
+    str += fmt.substr(text_pos, match_start - text_pos);
+    int r = snprintf(s, n, tokens_begin->str().c_str(), args.at(i)->value());
+    if (r < 0)
+    {
+      std::cerr << "format() error occurred: " << std::strerror(errno)
+                << std::endl;
       abort();
-  }
-  if (ret < 0 && errno != 0) {
-    std::cerr << "format() error occurred: " << std::strerror(errno) << std::endl;
-    abort();
-  }
-  return ret;
+    }
+    str += std::string(s);
+    text_pos = tokens_begin->position() + tokens_begin->length();
+    ++tokens_begin;
+    ++i;
+  }
+  str += fmt.substr(text_pos);
+  strncpy(s, str.c_str(), n);
+  return str.length();
 }
 
 BPFtrace::~BPFtrace()
@@ -573,7 +567,7 @@ void perf_event_printer(void *cb_cookie, void *data, int size __attribute__((unu
     }
 
     auto id = printf_id - asyncactionint(AsyncAction::syscall);
-    auto fmt = std::get<0>(bpftrace->system_args_[id]).c_str();
+    auto fmt = std::get<0>(bpftrace->system_args_[id]);
     auto args = std::get<1>(bpftrace->system_args_[id]);
     auto arg_values = bpftrace->get_arg_values(args, arg_data);
 
@@ -593,7 +587,7 @@ void perf_event_printer(void *cb_cookie, void *data, int size __attribute__((unu
   else if ( printf_id >= asyncactionint(AsyncAction::cat))
   {
     auto id = printf_id - asyncactionint(AsyncAction::cat);
-    auto fmt = std::get<0>(bpftrace->cat_args_[id]).c_str();
+    auto fmt = std::get<0>(bpftrace->cat_args_[id]);
     auto args = std::get<1>(bpftrace->cat_args_[id]);
     auto arg_values = bpftrace->get_arg_values(args, arg_data);
 
@@ -615,7 +609,7 @@ void perf_event_printer(void *cb_cookie, void *data, int size __attribute__((unu
   }
 
   // printf
-  auto fmt = std::get<0>(bpftrace->printf_args_[printf_id]).c_str();
+  auto fmt = std::get<0>(bpftrace->printf_args_[printf_id]);
   auto args = std::get<1>(bpftrace->printf_args_[printf_id]);
   auto arg_values = bpftrace->get_arg_values(args, arg_data);
 

tests/runtime/call

@@ -13,6 +13,11 @@ RUN bpftrace -v -e 'struct Foo { int a; char b[10]; } uprobe:testprogs/uprobe_te
 EXPECT 123 hello 456 world
 TIMEOUT 5
 
+NAME printf_more_arguments
+RUN bpftrace -v -e 'BEGIN { printf("%d: %s; %d: %s;; %d: %s;;; %d: %s;;;;\\n", 1, "a", 2, "ab", 3, "abc", 4, "abcd"); exit(); }'
+EXPECT 1: a; 2: ab;; 3: abc;;; 4: abcd;;;;
+TIMEOUT 5
+
 NAME time
 RUN bpftrace -v -e 'i:ms:1 { time("%H:%M:%S\n"); exit();}'
 EXPECT [0-9]*:[0-9]*:[0-9]*
@@ -87,6 +92,11 @@ RUN bpftrace --unsafe -v -e 'i:ms:100 { system("echo 'ok_system'"); exit();}'
 EXPECT ok_system
 TIMEOUT 5
 
+NAME system_more_args
+RUN bpftrace --unsafe -v -e 'i:ms:100 { system("echo %d %d %d %d %d %d %d", 1, 2, 3, 4, 5, 6, 7); exit();}'
+EXPECT 1 2 3 4 5 6 7
+TIMEOUT 5
+
 NAME count
 RUN bpftrace -v -e 'i:ms:100 { @ = count(); exit();}'
 EXPECT @:\s[0-9]+
@@ -151,6 +161,11 @@ RUN bpftrace -v -e 'i:ms:1 { cat("/proc/uptime"); exit();}'
 EXPECT [0-9]*.[0-9]* [0-9]*.[0-9]*
 TIMEOUT 5
 
+NAME cat_more_args
+RUN bpftrace -v -e 'i:ms:1 { cat("/%s%s%s%s/%s%s%s", "p", "r", "o", "c", "u", "p", "time"); exit();}'
+EXPECT [0-9]*.[0-9]* [0-9]*.[0-9]*
+TIMEOUT 5
+
 NAME uaddr
 RUN bpftrace -v -e 'uprobe:testprogs/uprobe_test:function1 { printf("0x%lx -- 0x%lx\n", *uaddr("GLOBAL_A"), *uaddr("GLOBAL_C")); exit(); }' -c ./testprogs/uprobe_test
 EXPECT 0x55555555 -- 0x33333333

tests/semantic_analyser.cpp

@@ -898,6 +898,9 @@ TEST(semantic_analyser, printf)
   test("kprobe:f { printf(\"%A\", comm) }", 10);
   test("kprobe:f { @x = printf(\"hi\") }", 1);
   test("kprobe:f { $x = printf(\"hi\") }", 1);
+  test("kprobe:f { printf(\"%d %d %d %d %d %d %d %d %d\", 1, 2, 3, 4, 5, 6, 7, "
+       "8, 9); }",
+       0);
 }
 
 TEST(semantic_analyser, system)