crystal-lang · Oct 12, 2016 · Oct 12, 2016
Showing with 26 additions and 3 deletions.

+9 −0 spec/std/file_spec.cr

+6 −0 spec/std/string_spec.cr

+6 −3 src/file.cr

+5 −0 src/string/builder.cr
diff --git a/spec/std/file_spec.cr b/spec/std/file_spec.cr
@@ -37,6 +37,15 @@ describe "File" do
     str.should eq("Hello World\n" * 20)
   end
 
+  {% if flag?(:linux) %}
+    it "reads entire file from proc virtual filesystem" do
+      str1 = File.open "/proc/self/cmdline", &.gets_to_end
+      str2 = File.read "/proc/self/cmdline"
+      str2.empty?.should be_false
+      str2.should eq(str1)
+    end
+  {% end %}
+
   it "reads lines from file" do
     lines = File.read_lines "#{__DIR__}/data/test_file.txt"
     lines.size.should eq(20)

diff --git a/spec/std/string_spec.cr b/spec/std/string_spec.cr
@@ -1846,6 +1846,12 @@ describe "String" do
     end
   end
 
+  it "raises if capacity too big on new with UInt32::MAX - String::HEADER_SIZE - 1" do
+    expect_raises(ArgumentError, "capacity too big") do
+      String.new(UInt32::MAX - String::HEADER_SIZE) { {0, 0} }
+    end
+  end
+
   it "raises if capacity too big on new with UInt64::MAX" do
     expect_raises(ArgumentError, "capacity too big") do
       String.new(UInt64::MAX) { {0, 0} }

diff --git a/src/file.cr b/src/file.cr
@@ -421,10 +421,13 @@ class File < IO::FileDescriptor
         file.set_encoding(encoding, invalid: invalid)
         file.gets_to_end
       else
+        # We try to read a string with an initialize capacity
+        # equal to the file's size, but the size might not be
+        # correct or even be zero (for example for /proc files)
         size = file.size.to_i
-        String.new(size) do |buffer|
-          file.read Slice.new(buffer, size)
-          {size.to_i, 0}
+        size = 256 if size == 0
+        String.build(size) do |io|
+          IO.copy(file, io)
         end
       end
     end

diff --git a/src/string/builder.cr b/src/string/builder.cr
@@ -13,6 +13,11 @@ class String::Builder
   def initialize(capacity : Int = 64)
     String.check_capacity_in_bounds(capacity)
 
+    # Make sure to also be able to hold
+    # the header size plus the trailing zero byte
+    capacity += String::HEADER_SIZE + 1
+    String.check_capacity_in_bounds(capacity)
+
     @buffer = GC.malloc_atomic(capacity.to_u32).as(UInt8*)
     @bytesize = 0
     @capacity = capacity.to_i