remove sfio versioning mechanism

The sfio library versioned its format structure, _sffmt_s. This allowed multiple
format structures of differing versions to exist in memory at once,¹ with sfio
able to distinguish between a structure created by itself vs a structure created
by a different version of sfio. In theory, this allows multiple versions of the
sfio library to be loaded at once.

In practice, Graphviz does not take advantage of any of this. In fact, it is not
possible to do this within Graphviz as SFIO_VERSION has not been bumped when
lib/sfio is changed. It still claims to be compatible with a version developed
in 2001.

This commit removes the versioning mechanism entirely, in order to both reduce
maintenance overhead as well as remove the runtime cost associated with managing
this data. The latter is trivial in terms of runtime, but it is also work that
has no purpose.

¹ This kind of design often also allows you to serialize a structure to disk or
  network to later be read back in by a potentially differing version of the
  library. In the case of sfio however, this use case was not possible because
  the structure contains function pointers.

diff --git a/lib/expr/exeval.c b/lib/expr/exeval.c
index 03742110f754156e697a064bd1638f8c4c753b8f..448ce6c358c201c9012afde3ff303e0d2606922c 100644 (file)
--- a/lib/expr/exeval.c
+++ b/lib/expr/exeval.c
@@ -403,7 +403,6 @@ print(Expr_t* ex, Exnode_t* expr, void* env, Sfio_t* sp)
                }
        }
        memset(&fmt, 0, sizeof(fmt));
-       fmt.fmt.version = SFIO_VERSION;
        fmt.fmt.extf = prformat;
        fmt.expr = ex;
        fmt.env = env;
@@ -530,7 +529,6 @@ scan(Expr_t* ex, Exnode_t* expr, void* env, Sfio_t* sp)
        }
  get:
        memset(&fmt, 0, sizeof(fmt));
-       fmt.fmt.version = SFIO_VERSION;
        fmt.fmt.extf = scformat;
        fmt.expr = ex;
        fmt.env = env;

diff --git a/lib/sfio/sfio.h b/lib/sfio/sfio.h
index 0a11d0a6e359d0422f3037ed028a55fd88fe716d..5decb1e3748cb39e90c990e772fe3998af3b7ced 100644 (file)
--- a/lib/sfio/sfio.h
+++ b/lib/sfio/sfio.h
@@ -15,8 +15,6 @@ extern "C" {
 #ifndef _SFIO_H
 #define _SFIO_H        1
 
-#define SFIO_VERSION   20010201L
-
 /*     Public header file for the sfio library
 **
 **     Written by Kiem-Phong Vo
@@ -80,7 +78,6 @@ extern "C" {
     typedef int (*Sffmtext_f)(Sfio_t *, void *, Sffmt_t *);
     typedef int (*Sffmtevent_f)(Sfio_t *, int, void *, Sffmt_t *);
     struct _sffmt_s {
-       long version;           /* version of this structure            */
        Sffmtext_f extf;        /* function to process arguments        */
        Sffmtevent_f eventf;    /* process events                       */
 
@@ -97,8 +94,6 @@ extern "C" {
        char *t_str;            /* type string                          */
        ssize_t n_str;          /* length of t_str                      */
     };
-#define sffmtversion(fe,type) \
-               (type ? ((fe)->version = SFIO_VERSION) : (fe)->version)
 
 #define SFFMT_SSHORT   00000010        /* 'hh' flag, char                     */
 #define SFFMT_TFLAG    00000020        /* 't' flag, ptrdiff_t                 */

diff --git a/lib/sfio/sftable.c b/lib/sfio/sftable.c
index 0b0b39b7e077cd2ec678338d668f06f8cfe25c99..2e68af083f8bcff18b26531a07b7fd912f938393 100644 (file)
--- a/lib/sfio/sftable.c
+++ b/lib/sfio/sftable.c
@@ -303,7 +303,6 @@ static Fmtpos_t *sffmtpos(Sfio_t * f, const char *form, va_list args,
        }
 
        if (ft && ft->extf) {
-           fp[n].ft.version = ft->version;
            fp[n].ft.extf = ft->extf;
            fp[n].ft.eventf = ft->eventf;
            if ((v = fp[n].need[FP_WIDTH]) >= 0 && v < n)