| This program, dist, is the bootstrapping tool for the Go distribution. |
| It takes care of building the C programs (like the Go compiler) and |
| the initial bootstrap copy of the go tool. It also serves as a catch-all |
| to replace odd jobs previously done with shell scripts. |
| |
| Dist is itself written in very simple C. All interaction with C libraries, |
| even standard C libraries, is confined to a single system-specific file |
| (plan9.c, unix.c, windows.c), to aid portability. Functionality needed |
| by other files should be exposed via the portability layer. Functions |
| in the portability layer begin with an x prefix when they would otherwise |
| use the same name as or be confused for an existing function. |
| For example, xprintf is the portable printf. |
| |
| By far the most common data types in dist are strings and arrays of |
| strings. Instead of using char* and char**, though, dist uses two named |
| data structures, Buf and Vec, which own all the data they point at. |
| The Buf operations are functions beginning with b; the Vec operations |
| are functions beginning with v. The basic form of any function declaring |
| Bufs or Vecs on the stack should be |
| |
| void |
| myfunc(void) |
| { |
| Buf b1, b2; |
| Vec v1; |
| |
| binit(&b1); |
| binit(&b2); |
| vinit(&v1); |
| |
| ... main code ... |
| bprintf(&b1, "hello, world"); |
| vadd(&v1, bstr(&b1)); // v1 takes a copy of its argument |
| bprintf(&b2, "another string"); |
| vadd(&v1, bstr(&b2)); // v1 now has two strings |
| |
| bfree(&b1); |
| bfree(&b2); |
| vfree(&v1); |
| } |
| |
| The binit/vinit calls prepare a buffer or vector for use, initializing the |
| data structures, and the bfree/vfree calls free any memory they are still |
| holding onto. Use of this idiom gives us lexically scoped allocations. |
| |
